Throw It In/Live-Action TV

"Listen to how Gibby delivers his line: 'Uh-oh! Looks like trouble off the stern... port... bow.' You'll notice how he seems confused and slows down at the end of that line. The reason? Noah ("Gibby") forgot the line as he was saying it! He couldn't remember how it ended. Later, when I watched it in editing, I felt it played really funny, so I used the take where he forgot the line."
 * Some of Saturday Night Live's most memorable moments are either this trope or Hilarious Outtakes that turn into Throw It In after much cracking up and struggling to keep composure. Of course, since it's a live show, if the moment happens for the first time during broadcast, Throw It In is the only option.
 * One of the earliest, and one of the most famous: during Chris Farley's "Matt Foley" sketch, guest star Christina Applegate and cast member David Spade can be seen trying (and failing miserably) not to laugh while Farley goads them on with his famous "I LIVE IN A VAN DOWN BY THE RIVER!" line. The confusion and smirking on Phil Hartman and Jan Hooks' faces are genuine, and the camera cuts to the cast members repeatedly laughing out loud.
 * Also thrown in was Chris Farley falling and smashing the living room table. That originally wasn't supposed to happen, but it was kept in because it was funny.
 * A lot of Chris Farley's ,most memorable moments on the show were Throw It In moments that stemmed from something bad happening on the set. When he played Weekend Update correspondent Bennett Brauer who used air quotes all the time, he suddenly found himself flying over the Weekend Update set (or, rather, about to, but ended up getting tangled in one of the stage lights. Farley ad-libs, "I have a weight problem. Can't they lift me?")
 * When Bill Hader couldn't stop cracking up during his lines as Stefon, he started covering his mouth with his hands. This was written in as a character tic.
 * The "Stefon" segments on "Weekend Update" are full of Throw It In, in the sense that John Mulaney (one of the writers) throws in a lot of changed jokes minutes before Hader's cue, often leading him to crack.
 * This often happened on Conan O Brien's Late Night as well. Whenever things went wrong (special effects not working, problems with costumes), Conan would often declare the screw-up to be better that what had originally been planned. In one particularly funny incident, a fire alarm went off in the middle of taping the show. Once it was established that there was no emergency, Conan decided to abandon the planned bit and air the resulting debacle. In another, when a technical glitch stalled a bit he was doing, Conan jumped up on his desk and began performing a striptease in order to pass the time until the problem was fixed.
 * A bizarre moment occurred during an interview with James Spader which was interrupted when a recording of a voice actor stating "Now that's a good Friday", apparently intended for a skit, was accidentally piped into the studio, leading to some good-natured ribbing of the production team.
 * Similarly, Craig Ferguson has left in a lot of bloopers. For instance, he's had the lights go out on him twice (once due to a power failure), and on another occasion, he slapped his Teleprompter too hard and shattered it.
 * The Game Show Super Password was almost ridiculously prone to set breakdowns, most of which were not edited out of the broadcast (for instance, the door sticking, the whole puzzleboard accidentally being revealed, etc.). To say nothing of Convy's utter inability to keep his mouth shut, which often led to him blurting out the puzzle answer prematurely and therefore leading to the whole round being scrapped.
 * An episode of The Jamie Foxx Show features Mark Curry guest starring as a traffic school instructor who takes his job far too seriously, reaching borderline drill sergeant levels, and eventually breaking into full-fledged military maniac troop leader. While one can't be sure, many of his gags seem improvised, such as one in which he walks into the classroom, trips, and stands up quickly, proclaiming "Any of y'all laugh, you ain't gonna graduate!" and another in which he slips while running towards Braxton's desk before loudly telling him what a "square" he is. In both instances, a number of the cast members couldn't help but laugh, including Jamie Foxx himself, and were forced to turn their heads away from the camera to conceal their laughter.
 * I Carly: On "iQuit iCarly", Dan Schneider remarks:

"Crow: [Having knocked off Tom's head during a martial arts duel] Uh-oh...I broke him."
 * Dan Schneider's propensity for throwing in elements of his previous shows in his newer ones was what led to the creation of the Nick Verse.
 * In Buffy the Vampire Slayer, Giles walks into a tree when Buffy reveals that she knows he had sex with her mother under the effects of magical chocolate. This was unrehearsed and done at the last minute, to comical effect.
 * Two more hilarious examples come from the first season episode, "The Puppet Show". Nicholas Brendon screaming "REDRUM!!!" while playing with the puppet suspected of being a killer was shot between takes and thrown in, while Willow suddenly running offstage during their talent show performance of Oedipus Rex was improvised by Alyson Hannigan.
 * In "Enemies", when the Mayor suggests miniature golf to take her mind off her troubles, Faith (Eliza Dushku) unscriptedly cracks up at the absurdity.
 * "... And I've been sleeping with Spike. Hilarity ensues.
 * On the commentary for the season 2 DVD of Scrubs, the creator comments that scenes written for the Janitor often had the addendum "or whatever Neil decides to say," due to his frequent habit of improvising usable material.
 * In John Ritter's guest spot, on Scrubs, he improvised the line "I pooed a little" after his pull my finger gag. Zach Braff immediately had to bite down on his cheeks to keep from laughing.
 * In the "STOP FINISHING MY AWESOME JOKES!" scene, J.D.'s "Oh, my God" while holding his ears was unscripted -- he actually didn't expect Sarah Chalke's voice to get as high-pitched as it did.
 * Mystery Science Theater 3000 examples:
 * The puppet characters occasionally malfunctioned; Tom Servo's head, in particular, would often fall off during production. Sometimes this worked well enough to keep; for example, in a sketch where Tom and Crow were Secret Service agents getting increasingly worked up about protecting Mike, Tom's bubble jarred loose and fell off at the climax, leading them to shout "HEAD! AHHHHHHH!" and panic.

"John Cleese: Penguins don't come from next door, they come from the Antarctic!
 * Perhaps the greatest example of this was during the riff filming for a first season episode, when Josh Weinstein, still performing Servo at the time, sneezed violently. Nobody missed a beat.
 * According to some accounts, Joel Hodgson was really tired during the filming of the first KTMA episode because he had stayed up late the night before building the set and the robots which caused Joel Robinson to have a dopey laid-back demeanor. The crew decided to keep this as a character trait for Joel. Other accounts, however, state that Hodgson had used the same laid-back character performance in his prop-comic standup long before MST3K.
 * As mentioned in the film section, ad-libs are rare in Monty Python's Flying Circus, but at least one has been noted. In the "Exploding Penguin on the TV Set" sketch, Graham Chapman got away with this exchange...

Graham Chapman: BURMA!

John Cleese: (looks around the room nervously, a genuine reaction) ... Why'd you say "Burma"?

Graham Chapman: I panicked."

""Watch out for those tempo changes, man, 'cause once we go into the second bridge, this shit takes off!""
 * The line intercourse the penguin was also thrown in by Graham Chapman. You can definitively tell that John Cleese wasn't expecting it.
 * Not an on-screen example, but Aaron Sorkin once ran across Allison Janney entertaining the cast and crew of The West Wing by lip-syncing to a jazz piece by Ronny Jordan called "The Jackal". He liked it so much he had Janney's character, CJ, do it in an episode, and had the characters imply that it was a ritual at the White House's victory parties.
 * Columbo's famous And Another Thing mannerism was a sort of Throw It In. While writing the play Prescription: Murder, which introduced the character, writers Levinson and Link had just written Columbo's exit from a scene when they realized they had forgotten to include an important plot point. Rather than retyping the whole scene, they simply had Columbo come back in and ask "one more thing".
 * In the original scripts for The Addams Family, Lurch was a mute -- but Ted Cassidy ad-libbed his Catch Phrase "You rang?" while filming the pilot, and the producers like it so much they gave Lurch a voice.
 * William Hartnell's habit of flubbing his lines on Doctor Who was left in due to limited budget. (If you watch carefully, many early episodes will be peppered with minor flubs, usually a slight but noticeable delay or stutter.)
 * And the actor playing Ian Chesterton was able to ad lib so well off of Hartnell's frequent hashings of the character's name that it was eventually written in the scripts that the Doctor would mispronounce it.
 * In "The Hand of Fear": after Sarah, she says "Eldrad must live!... Just testing." That was an ad-lib.
 * Colin Baker was personally responsible for several notorious puns during his time as the Doctor, including the "Perrier water" joke (punning on the name of his companion Peri) in "Vengeance on Varos", and the Doctor's "No 'arm in trying" in "Revelation of the Daleks", after.
 * Patrick Troughton frequently varied his lines or added unscripted business during his time as the Doctor, including the first ever Doctor/companion kiss.
 * The Doctor ripping off a strap in "The Time of Angels". First take was an accident but the producers loved it so they told Matt Smith to rip it off in subsequent takes.
 * In the Seinfeld episode "The Parking Garage," the characters spend almost the entire episode trying to find their parked car in a parking garage. The original ending was for them to find it at the end, drive off, but then be unable to find the exit to the mall. However, when filming the scene where they were supposed to drive off, the car wouldn't start up. Deciding that was funnier, they used that as the ending instead. If you look closely before they cut away to a long shot, you can see Julia-Louis Dreyfuss and Jason Alexander shaking with laughter as the car refuses to start.
 * In another episode, Jason Alexander sneezes just as Jerry tells him, "I blamed it on you." They felt it was funnier that way and kept it.
 * In "The Junior Mint", Jerry's line "We'll watch them slice this fat bastard up" was ad-libbed. You can see the actors holding back laughs when he says this.
 * Kramer's now-iconic sudden entrances into Jerry's apartment began when Richards was late for a cue during one of the first shows, and entered quickly through the door. The audience got such a kick out of it that he kept entering that way in subsequent episodes. It has become one of the character's most lasting trademarks.
 * In an exception to the comedy rule, the last episode of the third season of M*A*S*H had, at the end, the characters having a moment of silence At the very end of the scene, someone drops a tray of surgical supplies, shaking everyone from their thoughts; this was unscripted and just left in.
 * The broadcast version does not have the tray dropping; the scene fades out on Hawkeye and Trapper continuing their surgery without pause.
 * In Star Trek Voyager, non-Trekkie Robert Picardo ad-libbed "I'm a doctor, not a night light," in his audition for the role of The Doctor while having no conscious idea that "I'm a doctor, not a [something]" was Dr. McCoy's famous Catch Phrase. The particular line didn't make it into an episode, but was liked enough that The Doctor went on to use "I'm a doctor, not a [something]" phrases as much as McCoy had, and other Trek doctors would use it on rare occasion as well.
 * Similarly, Amanda Tapping was cast as Samantha Carter on Stargate SG-1 after ad-libbing how the dialing computer for the Stargate had been MacGyvered to work, since it was an acknowledgment of Richard Dean Anderson's previous role as MacGyver. Unlike the Star Trek example, this one was kept in.
 * The concept of Jaffa performing a meditation called "kel'no'reem" apparently was inspired by Christopher Judge falling asleep on set during one take, and Micheal Shanks quipping "Oh, he's not sleeping, he's meditating."
 * Farscape apparently had quite a bit of this going on, starting at around about the time Ben Browder ended a scene of armed guards chasing him by whirling around to face them, putting his gun to his own head, and shouting "Nobody move or the white boy gets it!"
 * In Gigi Egley's first appearance as Chiana, the character wasn't intended to stay on the show so she was given painful contact lenses that severely restricted her vision. When it was decided to make her a main character the lenses were modified to be more comfortable, but all the exaggerated head movements Egley had done to be able to see what she was doing were kept in as a character trait.
 * The Grand Finale of Star Trek Deep Space Nine has one of these involving the villain-turned-not-quite-hero-but-honorable-and-somewhat-admirable-leader Damar. When he and his followers storm the Dominion HQ on Cardassia, he is fatally wounded. His final word was "Keep..." That was not scripted -- the actor who played Damar felt that a silent death scene wasn't right. And even he isn't sure how he would have finished the line.
 * At the end of a sketch on The Electric Company where Rita Moreno plays a director trying to get Bill Cosby to get his line right, Morgan Freeman cracks up and walks off the set.
 * And in another sketch about a boxing match between the letter combinations "ea" and "ee", Cosby is handed a trophy... which falls apart in his hands accidentally. Skip Hinnant ad-libs: "Sorry we couldn't have sprung for a better trophy." Morgan Freeman cracks up again.
 * This article talks of One Life to Live having unscripted interactions between real-life drug addicts and one of the characters.
 * The Red Dwarf episode "D.N.A." has a scene where Rimmer, planning to clone himself to come back to life, is examining some of his own dandruff under a microscope while the Cat looks over his shoulder. During a rehearsal, Danny John-Jules accidentally sneezed on the microscope at the end of the scene. The timing was so perfect that the writers put it in the episode.
 * In another moment courtesy of Danny John-Jules, the episode "Bodyswap" features Lister's brain being recorded onto a cassette tape and given to the Cat for safekeeping. Almost immediately, he accidentally drops it in his mug of coffee.
 * From Quarantine, when Lister, Kryten and Cat are using the luck virus to locate what they need to fight Rimmer and Mr. Flibble, Craig Charles collides with and almost trips over the second item. The DVD commentary suggests that wasn't intentional.
 * Craig again, from Holoship. Lister eating the cigarette at the end of the confrontation with a hologram wasn't part of the episode script. Apparently he was sick after the scene.
 * "I don't know why I ate that fucking cigarette!"
 * For Holly's return to the cast in Nanarchy, he had to give a complicated explanation of the episode's events. According to a later interview, Norman Lovett couldn't pronounce a particularly difficult word in the script, which was Holly-ish enough to make it into the episode as 'that word I can't say'.
 * In the Supernatural episode "In The Beginning," Samuel is being possessed by the YED and after Dean unwittingly tells him everything, he pins Dean to the wall and smells his neck while asking him if he's one of the "special children." According to Mitch Pileggi, the neck-smelling wasn't rehearsed beforehand so Dean's squicked-out reaction is completely genuine and the sexual Subtext is even more creepy.
 * Another example is Misha Collins' first appearance as Castiel. The staring and ignoring Dean's personal space was not scripted, so that Jensen Ackles was genuinely surprised.
 * And in "Bad Day at Black Rock," Dean's final frustrated "SON OF A BITCH!" was an ad-lib by Jensen Ackles, and you can clearly see Jared Padalecki breaking character and laughing.
 * How about throwing in an entire interpretation of a character? As noted under Playing Against Type, Marc Warren, known for smooth cockney scoundrel Danny in Hustle played a frightening Psychopathic Manchild as Jonathan Teatime in Hogfather. What's interesting is that he was hired to play Teatime similarly to Danny, but instead chose an interpretation inspired by Johnny Depp's creepy Michael Jackson-esque Willy Wonka. And it works horrifyingly well.
 * In a form of inversion, Yes Minister star Paul Eddington had a number of lines cut after he demonstrated that he was capable of expressing everything of significance in the discussion with expressions alone, particularly in the later episodes.
 * While most of Whose Line Is It Anyway is improvised to begin with, the 100th episode had a notable incident where the electronically-synthesized bass rhythm suddenly sped up in the middle of a song, and Hilarity Ensued. They redid the game with the intention of throwing out the first take, but in the end, the second take was thrown out and the first take was used. It featured Wayne trying to spell out the subject's name "Howard" in rhythm, and being flustered from the tempo change he ended up spelling out H-O-R-W-A-R-D. Drew gave him a hard time about it, leading to Wayne responding "It's hard to spell at 210 beats per minute."
 * Greg Proops, afterwards:

"Kathy: "Are you Carol Channing?"
 * And later on came the "broken desk light" incident. During a "Party Quirks" game, Ryan's quirk was that he was Carol Channing, whose head keeps sticking to things. Ryan, at one point, acts like his head is drawn to Drew Carey's dais. Ryan's head slams into the rectangular light built into the front of the dais, shattering it. Everyone else cannot control their laughter, and the game eventually ends when his quirk is figured out. During the whole ordeal, Ryan stayed in character even with broken glass in his hair. And yes, the game was aired as it was.

Ryan: "Well I used to be I can't remember anymore.""

"Joey: Guess what job I just got?
 * Should any of the performers, Drew especially, say or do anything while between games that is hilarious, it will become a running gag for the remainder of the show.
 * One of the best known is when Drew flubbed a line from a scripted card, introducing "African Chant", and stated that "Africa is a country". Greg Proops, the forth chair that episode, busted up and immediately corrected him that, "It's also a continent, if you're a geographer!." Drew didn't live that down for the rest of the show.
 * One had Drew using a tape recorder of himself saying "One Thousand Points!" in an effort to do as little as possible. This provided two instances. One was pointing out the idiocy of making himself obsolete, especially as he needed to rewind the tape. Another was Wayne Brady editing the tape between segments to say "My ass! My ass! My ass!"
 * An audience member got one: When asked for a pair of unlikely roommates, a member loudly yelled out "Cosby and Hitler", prompting jokes the rest of the night. Most were directed at the producer who nixed the idea from making it to the screen.
 * In an early season two episode of House, House is mad at Wilson for having sided with Stacey, and Hugh Laurie ad-libbed "Bros before hos, man" during one take. You can clearly see Robert Sean Leonard cracking up at the line.
 * The famous "foot in the face" scene in the Merlin episode The Moment of Truth was at least partly just a joke Bradley James came up with -- he deliberately waited for Colin Morgan's take, and then... stuck his bare foot in his face. The disgusted reaction is completely genuine, and they did a take without it, though thankfully that's not what ended up in the episode.
 * Sifl and Olly often had these moments whenever one of the duo would laugh. These moments were usually caused by Liam Lynch. An example can be seen in the music video for "Baby For Gravy". These were also very common in segments featuring the character Chester.
 * During the twin fight in Skins, Kathryn Prescott and Giles Thomas were supposed to just make it look like Emily hit Doug; however, Kathryn got a little too into the scene and inadvertently lamped him. Giles was so gobsmacked that, in his subsequent confusion and surprise, he trod on Megan Prescott (Katie)'s foot, who spent the rest of the scene desperately trying not to cry. All of that made it to the final cut.
 * The ending of the famous Oilz scene was reportedly the result of Kathryn Prescott and Lily Loveless just going nuts.
 * According to Mark Harmon, the first-ever Gibbs Slap wasn't scripted; he just broke off in the middle of a scene to whack Michael Weatherly on the back of the head. Not only was it not cut, it rapidly became one of the character's trademarks.
 * Also, in "The Voyeur's Web", the scene where  was spontaneous. Pauley Perrette apparently forgot that Gibbs was supposed to be ignoring her and did it as a joke. It was left in.
 * In the first Christmas episode of That 70s Show, Kelso (Ashton Kutcher) spots Laurie, runs towards her, tries to jump over the couch, but slips on it and hurts his legs with the table, almost knocking over the punch bowl that was on it. Kutcher however manages to keep the straight face and to continue the scene afterwards. This shot was kept, and Kelso's hurting himself later became his trademark.
 * Behind-the-scenes materials indicate that Kutcher usually tried to roll with goof-ups - like his popsicle breaking in one episode - as just part of Kelso's clumsiness
 * In the episode where Donna tries to convince Jackie to move in with her, she at one point says: "Jackie, help me be more like you" and she sounds weirdly when she says it (like if she is running out of breath, or trying to hold a burp, or both). After a few more unsuccessful shots where neither Laura Prepon (Donna) nor Mila Kunis (Jackie) could keep from laughing, the first shot was kept.
 * The first time in "The Circle", Danny Masterson started cracking up while explaining how the government was hiding engines that ran on water. This wasn't scripted.
 * When filming the fifth episode of Glee, when Kristin Chenoweth (April) finishes her first take of "Maybe This Time", Chris Colfer actually cries at her performance. He was surprised to find out that they would use a shot of him crying as his character Kurt's reaction to April's performance.
 * Speaking of Glee, Brittany's non-sequiturs were all ad-libbed at first, and the confused stares she got from the others were real. And thus her famous Dumb Blonde persona was born.
 * Chris Colfer ad-libbing again: At the beginning of the second episode, when Puck and the other jocks are about to throw him into a dumpster, Kurt glares at them with contempt and says: "One day, you'll all work for me."
 * More broadly, the character Kurt Hummel can be considered this. Chris Colfer actually auditioned for the role of Artie, but the show's creators were so impressed by his talent and charm that they wrote an entirely new character loosely based on the openly gay actor.
 * In one episode of The Nanny, Sylvia fills in for Fran as the nanny. When she sits on Maxwell's desk (one of Fran's trademark moves), the desk collapses under her weight. They decided to keep it because it was funnier than what was originally scripted. If you look carefully, you can see the actors in the scene trying to not laugh.
 * An episode of Friends dealt with a woman calling Chandler and Joey believing she's calling a guy named Bob, and Chandler picks up, pretends to be Bob, sets up a meeting with her and then shows up to win her over when she's "stood up". The tag scene for that episode had the woman calling again, looking for Bob, this time with Joey hearing the message. The script called for Joey to pick up and say "Bob here", but Matt LeBlanc tripped and fell, desperately trying to grab the phone as he went down. This ended up a lot funnier than the scripted version and was kept for the episode.
 * In the episode "The One With Phoebe's Uterus", Joey walks into the apartment wearing a blue blazer. Matthew Perry (Chandler), while making a joke, accidently said "black" instead of "back", but the actors' reactions to the mistake were so funny, they decided to put it in the episode:

Chandler: I don't know, but Donald Trump wants his blue blazer black. (pauses)

Ross: What?

Chandler: Blue blazer back. He wants it back.

Rachel: But, you said "black". Why would he want his blue blazer black?

Chandler: Well, you know what I meant.

Monica: No, you messed it up. You're stupid.

Chandler: (changing the subject) So what job did you get, Joe?"

"Charlie: I know how to spell the word "anomaly", okay?
 * Similarly, in an episode of Frasier, Kelsey Grammer is supposed to rattle off the line "Fault-finding, flaw-fleeing Frasier" and end the scene by striking a confident pose, but he accidentally says "Flasier" instead. David Hyde Pierce proceeds to make fun of him, still in-character, ("You said 'Flasier'!", with a Niles-esque smug grin), and Grammer responds also in-character, protesting that did not say "Flasier", since he's been saying his own name for forty-some-odd years. The two then ad-lib talking over each other, tailing off into one of Niles and Frasier's very frequent scene-fade-out squabbles. Ironically, Grammer saying "forty-some-odd years" instead of whatever Frasier's exact age was (Grammer probably didn't know it off the top of his head) was completely appropriate in the context of the preceding conversation.
 * In the season three finale of How I Met Your Mother Barney is in a meeting with a bunch of Japanese men when Lily calls him to tell him that . He gets up, tells them in Japanese that his best friend needs him and he has to go, and hurries out the door. One of the men then turns to the others and asks, in English, "What did he say?" That line was ad-libbed during rehearsals by one of the extras in the scene, however it was given to one of the others to say in the actual episode.
 * Battlestar Galactica Reimagined (the 2000's series) had a lot of this too... a fair amount of it probably stemmed from Edward James Olmos' method acting. The most famous Throw It In was probably the scene when in a fit of rage, Olmos-as-Adama destroyed a very expensive model ship that was on loan from a maritime museum.
 * When Roslin promotes Adama to Admiral, she was supposed to kiss him on the cheek. Olmos kissed her on the lips instead, and it was used in the episode. Mary McDonnell would later go on to say that she believes it is during that scene that Roslin falls in love with Adama, although it would take them another two seasons to get around to admitting it.
 * Grace Park threw in the lullaby that Boomer hums to the Raider and Athena hums to Hera, which is a traditional Korean lullaby.
 * Gaeta's savage baiting of Starbuck with the line "I suppose a pity frak is out of the question, then?" at the end of their mess-hall conversation in the episode 'A Disquiet Follows My Soul' was improvised on the first take by Alessandro Juliani. The entire set cracked up; then Ron Moore decided he liked it and asked AJ to keep it in in subsequent takes.
 * In Numb3rs David Krumholtz inadvertently misspelled "anomaly" as "anomoly" on a map in one scene in the pilot episode, which the writers and producers kept as a quirk for Charlie. They even reference it in the final episode of the first season:

Don: No, you don't.

Charlie: Get a dictionary. [...]

Don: (shows him the dictionary) See? One O.

Charlie: Is this a reliable dictionary?"

""Try Scrabble. He's a horrible speller.""
 * Also referenced by other characters throughout the show. For example, Alan confides in Larry that he hates playing chess with Charlie because he seems so bored, so Larry tells Alan:

"Blair: But, can you say it twice? No I'm serious, say it twice.
 * In Defying Gravity Wass's remark that he could "sleep through World War IV" caused a lot of fannish speculation as to whether this was a hint of the state of the world in 2052. When creator James Parriott was asked about it however, he claims not to remember writing the line, and that it must have been a throw in by the actor.
 * In the final scene of Gossip Girl's second season Chuck was supposed to tell Blair "I love you too" and then, after she kisses him, "I'm not Chuck Bass without you." The second line ended up being moved to the season three premiere, since they instead went with a take where the actors ad-libbed the following:

Chuck! I love you. I love you. That's three. Here's four -- I love you."


 * According to this page, the first episode of the cop show Matlock Police (not to be confused with the more famous Matlock) had a car chase, where "the more dramatic aspects of it happened by accident -- literally." (See link for details.)
 * In a Sex and The City episode, Miranda is contemplating her "just friends" relationship with on-again, off-again boyfriend Steve (who is the father of their son Brady). In an earlier scene in the episode, Steve picks Miranda's favorite flower, lilacs. Later in the episode, she's at a wedding, and, setting, a sprig of Lilac onto a table, asks her 1-year-old son Brady, whom she's holding, whether she ought to give Steve another chance. A second later Brady stretches out his hand for the flowers and picks them back up. This was unscripted, and worked for the scene particularly well.
 * In the CSI: NY episode "'Til Death Do We Part", Mac comes in to the lab to talk to Stella. At the end of the scene, someone comes in and gives Stella a crucial piece of evidence, to which she says "Best part of the job" and kisses Mac on the cheek. According to Melina Kanakaredes, who plays Stella, while filming that scene, she just spontaneously kissed Gary Sinise on the cheek and they decided to keep it in.
 * Just prior to the filming of the pilot for WKRP in Cincinnati, actor Richard Sanders (playing Les Nessman) injured himself, and thus appears in the pilot with a very visible bandage. It became a hallmark of the character that, in every subsequent appearance of the character, he always had some sort of visible bandage somewhere on his person.
 * David Lynch was famous for incorporating a number of Throw It In moments into Twin Peaks, including one which introduced a major plot element: during filming of the pilot episode, the face of Frank Silva, one of the set workers, was accidentally caught on camera reflected in a mirror. Lynch liked the effect enough to keep it in, and later cast Silva as BOB, the malevolent spirit . In addition, a number of improvisations and line-fumbles were kept in, even when they didn't actually make sense in context, in order to enhance the general weirdness of the show.
 * As much as 90% of Let the Blood Run Free was this, as the scripts were written based on audience votes, so the cast (all veterans of the original improv show) wouldn't see them until days before the episode aired.
 * Star Trek the Next Generation had a season one episode, "Symbiosis", where in one of the last scenes Tasha Yar is in the background. Blink and you'll miss it, she waves at the camera. This was the last episode filmed with Denise Crosby as a regular cast member. The next episode, "Skin of Evil", where the character leaves, was filmed before "Symbiosis".
 * A physical example occurs in The Sarah Connor Chronicles pilot episode, where Cameron has a mark across the side of her face where she was damaged in a fight scene. In reality, that injury was real; Summer Glau was hit in the face with an ejected brass casing while at the shooting range. Instead of covering up the mark, Summer decided to integrate it as one of the wounds she'd suffered in combat, and it shows throughout the pilot.
 * One of the most badass of all time: in the Breaking Bad episode "Crazy Handful of Nothing," Raymond Cruz improvised stubbing out a cigarette on his tongue. Bryan Cranston's reaction is quite genuine.
 * The opening of the MacGyver episode "Deathlock" shows a helicopter very nearly losing control due to ground resonance. However, the pilot averts disaster by lifting off, and the actors seem none the wiser.
 * When filming one of the pilots for Wheel of Fortune, the puzzle board was originally intended to be mechanical and self-revealing, like the board on Concentration. There wasn't enough time to finish building it, so the producers just had Susan Stafford turn the letters manually. After the show got picked up, they kept the board as it was. Of course, the letter-turning position was later taken over by the iconic Vanna White.
 * While filming the scene from the pilot of The Borgias where Rodrigo Borgia is elected Pope, Jeremy Irons decided to gleefully kiss Cardinals Orsini and della Rovere on the mouth. The looks on Colm Feore and Derek Jacobi's faces are priceless.
 * A fourth-season episode of The Fresh Prince of Bel Air has Will's (Will Smith) father, Lou, return to make amends after leaving him and his mother long ago. At the end of the episode, Lou ends up making another excuse to leave again, and Will is left with Uncle Phil. Will then launches into a scripted monologue where he expresses frustration that he wasted money buying a present. According to interviews from the cast and crew, directly after his monologue finished, Smith launched into an impromptu speech (where he shouts at Phil that he can handle himself without a father figure, and expresses that he'll be a better man than his father) based on his own experiences as a child. The speech was so powerful (James Avery gives a look of confusion when Will begins his speech before playing along, and an audience member can even be heard crying in the background during the final shot) that it was kept in the final episode as is.
 * Much of Mork's lines on Mork and Mindy were nothing but this. The writers would actually leave whole pages of the script blank and just let Robin Williams do what he wanted.
 * Similarly, according to the book Odd Couple Mania, there were numerous times on that show where blank script pages are preceded by the phrase "Oscar teaches Felix". Tony Randall and Jack Klugman would then improvise the teaching scene.
 * In the first episode of Leverage there is a scene establishing the Unresolved Sexual Tension between Nate and Sophie and Hardison rolls by on an office chair saying "oooooh...." Aldis Hodge wasn't even in the scene but had stuck around to watch.
 * Leverage is full of this trope.
 * Th Iceman Job has Hardison asking Eliot to "hug it out," it being the conflict brought about by Hardison's Big Lipped Alligator grift persona. Christian Kane is clearly surprised by the attempt at hugging.
 * In the Rashomon Job, Parker's victory dance/weapon brandish is ad-libbed.
 * Ditto The hug which Eliot gives Hardison as Hardison stands with his arms open after Parker obliviously walks away from his attempt to hug her.
 * "High five for morale," after The Gone Fishin' Job. Word of God states that the actors throw it in once in a while as an indicator of how much the friendship between the two Vitriolic Best Friends has evolved.


 * The studio audience for the All in The Family episode "Edith's 50th Birthday," in which Edith is nearly raped by an intruder, became so enraged at watching a beloved character under attack that when Edith hits her attacker with a cake pan and runs for the front door, a number of women in the audience can be heard screaming "RUN!"
 * David Dukes, who played Edith's would-be rapist, stated that the audience grew so hostile during the filming of this episode, he was afraid that audience members would rush onto the set and attack him.
 * The scene in Arrested Development episode, Motherboy XXX, shows Buster accidentally slamming the door on Michael's face as they go after Lucille. This was unplanned but the director liked Michael's reaction that it was allowed in the final cut.
 * The cast of The Office often improvises much to the surprise of the staff. In one episode, where Michael wants to prove to Oscar that he's not homophobic, forces himself to kiss him. The awkwardness was not scripted and the actor's reactions seen were genuine.
 * Another episode shows a Cold Opening where Jim wants to annoy Dwight by popping his balloon chair. The script was hoping that the balloon would deflate but the sudden popping and the surprised reactions were thought to be funnier.
 * On the Colgate Comedy Hour anything funny which came up during pre-show rehearsal would likely be written into the script.
 * On the Panel Game Jokers Wild, chairman Barry Cryer quite frequently made small slip-ups regarding the amount of points awarded, who was speaking at the moment, the subject and so on. This could have passed quite unnoticed, except the panel kept insisting on calling attention to these mistakes...he had two catchphrases to lampshade this: "I only said that to see if you were paying attention" and "Tune in next week; I won't be here."
 * In an episode of The Goodies, Graeme and Bill have just had a fight with Tim, and attempt to leave the room in a huff...but break down crying on the way out. Tim loudly mentions how he could use someone to work for him, at which point they both barrel back into the room. Fairly ordinary stuff...except Graeme slipped on the carpet while running back in, slid momentarily, and grabbed onto Tim to keep from falling over, nearly knocking him down on the process. They kept on with the scene as scripted, and it was kept in the final cut -- you can see Bill covering his face to stop himself giggling.