Suspiciously Similar Song/Film

Several places in the soundtrack of TITANIC, such as at 0:50 of Southampton, and the entire soundtrack of composer Joel Mcneely's DISNEY'S IRON WILL, is suspiciously similar to Stephen Foster's classic song Jeanie With The light Brown Hair.
The song LET'S ALL SING LIKE THE BIRDIES SING in Disneyland/Disney World's Enchanted Tiki Room is suspiciously similar to Offenbach's BARCAROLLE from The Tales Of Hoffmann (also called BELLE NUIT from Les Comtes d'Hoffmann).
Several parts of James Horner's Stealing The Enterprise, Battle In The Mutura Nebula, and Genesis Countdown in Star Trek II the Wrath of Khan and Star Trek III the Search For Spock was later reused in his own score for the The Rocketeer and parts of the score was reused in Walt Disney World's Fountain of Nations in E.P.C.O.T. Center.
The first part of "Hedwig's Theme" from Harry Potter is similar to Greensleeves.
James Horner's four-note "danger motif" is put in freakin' EVERYTHING (Willow (starting at 0:34), Enemy at the Gates (0:32), Troy, Avatar (5:24), Star Trek II (1:10), etc.), but it isn't even something he came up with! It's originally from Sergei Rachmaninoff's first symphony.
The Phantom Menace uses a knockoff of the third movement of Dvorak's ninth symphony in the lightsaber battle at the end.
- John Williams has done it before; the Imperial March from The Empire Strikes Back (and just about every subsequent movie in the series) is lifted heavily from Gustav Holst's Mars: Bringer of War movement from The Planets. The metre is changed and the order of the themes is mixed up a bit, but the similarities are fairly striking.
  - Especially during the Battle of Yavin, which also interpolates part of Jupiter: The Bringer of Jollity during the "X Wings Draw Fire" segment.
Also, "Across the Stars", the love theme from Attack of the Clones, is a Shout-Out by John Williams to Nino Rota's theme from the 1968 film of Romeo and Juliet.
The Imperial March (Darth Vader's theme) from The Empire Strikes Back is suspiciously similar to the third movement of Frédéric Chopin's Piano Sonata No. 2 in B-flat minor, Op. 35...the part known as Chopin's Funeral March.
"Augie's Great Municipal Band" music in the same movie is suspiciously similar to "The Emperor" music in Return of the Jedi. Part of the "A New Hope" music in Revenge of the Sith is suspiciously similar to of "Hedwig's Theme" from the Harry Potter series.
- Although in the case of the former, that's the whole point. It's intended to invoke the Emperor's theme, the newly-elected Chancellor Palpatine being the Emperor and all.
A Suspiciously Similar Song to of Queen's "Who Wants To Live Forever?" shows up in the movie Highlander II the Quickening.
The short film George Lucas in Love (a pastiche of Shakespeare in Love) has a Suspiciously Similar Song to the Star Wars theme for the end credits music.
"Make 'Em Laugh" from Singin in The Rain bears more than a small resemblance to Cole Porter's "Be a Clown", which had appeared a few years earlier in MGM's The Pirate.
Gone with the Wind uses a Suspiciously Similar Song to Offenbach's "Galop Infernal" (or "Can-Can") in a restaurant Scarlett and Rhett visit when dating - for some reason, since it's a public domain song (and probably was even back when it was filmed).
The "Parlay" music from the third Pirates of the Caribbean sounded very much like Ennio Morricone's Harmonica music. In fact, it was intentionally used to "give an air of the end of an era.
Angels Revenge features a triumphant melody that's not Also Sprach Zarathustra.
- And later on, the background music sounds suspiciously like the Charlie's Angels theme...
Starship Troopers 2: Hero of the Federation 's theme was similar to Backdraft's Fighting Seventeenth...
Woody Allen's 1969 comedy Take the Money and Run has an escape scene accompanied by a knockoff of Quincy Jones' "Soul Bossa Nova".
The James Bond theme is actually a Suspiciously Similar Song to an unused song composer Monty Norman wrote for a musical.
The Ghostbusters theme was suspiciously similar to "I Want A New Drug" by Huey Lewis and The News, and Huey actually sued Ray Parker Jr. over it.
- The same riff was first used in "Pop Musik" by the band M.
- Another Ghostbusters example would be the main theme for Filmations Ghostbusters, which in was was based on Edvard Grieg's "In the Hall of the Mountain King."
Alex North's original score for 2001: A Space Odyssey opened with a Suspiciously Similar Song to "Also Sprach Zarathustra", which was eventually used in the final version instead.
The music that they're trying to pass off as not-'Shaft'" from the Tank Girl movie.
The theme from The Natural is similar to Aaron Copland's "Fanfare for the Common Man".
The music in Star Wars: The Clone Wars sounds kind of like this when compared to the music from the films.
Brad Bird originally wanted John Barry to score The Incredibles, and used Barry's theme from On Her Majesty's Secret Service in the first trailer. When Michael Giacchino was hired after Barry turned out to be unavailable, the opening fanfare for the theme he wrote closely resembles the On Her Majesty's Secret Service theme.
The rape/seduction scene in Akira Kurosawa's Rashomon is set to music that sounds suspiciously like Ravel's Bolero. The composer claimed he wanted to create something that sounded more original (and more appropriately Japanese) but Kurosawa kept pushing him back towards Bolero.
The "Stairway to Heaven" scene from Wayne's World uses a Suspiciously Similar Song in the home video version. In the original theatrical release, they used the actual "Stairway" intro.
The end theme of The Lawnmower Man is only a couple notes off from being the Terminator theme.
Jerry Goldsmith's theme for the Supergirl movie intentionally matches the style of John Williams' Superman theme. In fact, almost every adaptation of Superman after 1978 has used a Suspiciously Similar Song to the Williams theme: see under Live Action TV and Western Animation. The same goes for parodies of course, e.g. as part of a cartoon episode.
Baz Luhrmann's William Shakespeares Romeo and Juliet has "O Verona", which is suspiciously similar to "O Fortuna" from Carmina Burana.
The cultists performing a human sacrifice in Young Sherlock Holmes (not to be confused with the other Sherlock Holmes movie with cultists performing a human sacrifice) chant a song which also rips off "O Fortuna".
In the movie adaptation of Ghost World, the character Doug blares some heavy metal from his car stereo - it sounds a lot like an instrumental knockoff of Metallica's "Master Of Puppets".
Leonard Rosenman's theme for RoboCop 2 is suspiciously similar to Basil Poleduris's theme from the original RoboCop.
In David Lynch's film of Dune, the scenes set on Caladan are scored with ambient string music that sounds a lot like the first movement of Dmitri Shostakovich's 11th Symphony, although the resemblance may not necessarily be intentional.
Spaceballs more or less did this with the Star Wars theme.
The original teaser trailer for UHF, meant to parody the Indiana Jones franchise, used an intentionally-obvious knockoff of the theme.
Averted hard in The Room, in which Tommy Wiseau shelled out the money for the rights to Happy Birthday to You.
The famous Jaws theme is actually very similar to the beginning of the fourth movement of Dvorak's New World Symphony. The two sound completely different after the first few notes, however.
The original version of French Canadian film Elvis Gratton used many songs by Elvis Presley. It has been replaced by instrumental Suspiciously Similar Songs.
John Travolto... da un Insolito Destino is parody/exploitation disco movie set (and filmed) during the Saturday Night Fever era about a John Travolta lookalike. Most of the score sounds like some other disco hits of the time. Halfway through this clip, you can hear that "It sounds like Staying Alive from The Bee Gees but it's not" music.
Muppet Treasure Island's "Treasure Island" piece seem to have inspired some of the music in Pirates of the Caribbean: the middle segment of The Black Pearl (skip to 52:00) and, less clearly, the violin playing at the He's a Pirate.
- Speaking of Hans Zimmer, the soundtrack from The Rock is very similar to the score from Pirates of the Caribbean: Curse of the Black Pearl. (For those not in the know, Zimmer worked on both).
The opening credits music for WarGames is a slightly tweaked version of the overture to Georges Bizet's opera Carmen.
In the scene in Bill and Teds Excellent Adventure when the two play Poker against Billy the Kid, the music is a very unsubtle rip-off of 'Il Triello' from The Good, the Bad and the Ugly. Similarly, the song "In Time" from the movie's soundtrack sounds very similar to "With or Without You" by U2.
The opening song to Orgazmo, Now You're A Man, has elements of "You Give Love A Bad Name" by Bon Jovi, Ronnie James Dio songs and "Eye of The Tiger",
The bridge section in John Williams' theme for Jurassic Park resembles a major-key transposition of Fugue no. 2 from Book 1 of Bach's The Well-Tempered Clavier.
- A similar motif can be heard in "The Key to the Gates of Heaven" from Andrew Lloyd Webber's musical Whistle Down the Wind: "Open up the gates, open up the gates, we've got to find the key...."
- Sesame Street uses the unmodified tune of Fugue no. 2 for the "Monsterpiece Theatre" theme: "ABCDE, EFGHI, HIJKLMN, O-oP...."
The fight theme from the unreleased The Fantastic Four by Eric and David Wurst is basically John William's "Here They Come" from Star Wars. While the Theme song is more or less shades of "the Main Theme" from Jurassic Park.
Somewhat averted in the DVD release of Where The Buffalo Roam, as the new songs don't sound anything like the ones used in the original movie. Still pretty lame, though.
The trailer for the film The Mask uses a Suspiciously Similar Song to the Danny Elfman composition "Breakfast Machine" from Pee Wees Big Adventure.
A home-video trailer for the second The Mighty Ducks film uses a painfully obvious Suspiciously Similar Song to the theme from Back to The Future.
The theme from Kinji Fukasaku's Blackmail Is My Life, which appears throughout the film, is a wordless soundalike of "Over Under Sideways Down" by the Yardbirds.
The music in the second Bibi Blocksberg movie sounds suspiciously similar to Hedwig's Theme from the Harry Potter films.
"Thank You Very Much" from Scrooge sounds similar to "A Bushel and a Peck" from Guys and Dolls.
"It's Our Fight" from Transformers: Dark Of The Moon sounds a lot like "Mind Heist" from the Inception trailer. Zack Hemsey, the composer of "Mind Heist", even called attention to it on his blog.
This trailer for the 2011 Muppets movie -- which parodies a The Girl With the Dragon Tattoo trailer -- lampshades this, with intertitles that read:

We couldn't / get the rights / to the real / song / so we had / some dude / write / this one / but we / had to / put him / in the / movie. / Here he is. / (shot of crowd scene with one person in the background circled) Totally/ Worth It

In the first Alvin and the Chipmunks movie, Dave's demo song is suspiciously similar to Death Cab for Cutie's "I Will Follow You Into the Dark".
The Mortal Kombat theme sounds suspiciously like 2 Unlimited's "Twilight Zone". Of course they're the same orchestra hit stadium techno style so there's bound to be resemblance.
The opening credits to Freddy's Dead: The Final Nightmare features music that sounds very similar to "Night On Bald Mountain" by Modest Mussorgsky. Almost to the point, that you'd swear it actually was "Night on Bald Mountain."
As part of it's And You Were There sequence, loose The Wonderful Wizard of Oz adaptation The Witches Of Oz features a street musician ( the wizard himself) playing a clarinet tune that's just similar enough to "Somewhere Over The Rainbow" to be recognizable.