Info Drop

Sometimes the most interesting revelations aren't delivered with a dramatic speech, a round of shocked expressions and a title card reading "to be continued". Sometimes they're just handed out casually, tossed in the audience's face without fanfare or even a helpful sign saying "this is important". In many cases, it's not until Fridge Logic kicks in that the audience has a chance to react.

These are Info Drops, which are to Infodumps what a single stealth paratrooper is to a nuclear warhead.

While rarely relevant to the actual plot, an Info Drop usually fleshes out subtle details of the setting and/or characters, usually nagging questions that will continue to nag the less-attentive. For instance, say a character has Only One Name; there might be an Info Drop where he writes his full name on a check, or perhaps someone calls out his missing surname (or given name), and this is the one and only time it's either seen or referenced. Or perhaps it's never explicitly said when the story takes place, but there is a date that appears somewhere that can be cross-referenced with the events of the story.

Contrast Cryptic Background Reference, where a Noodle Incident is used to add the illusion of depth to the story's background without actually adding any extra detail.

Examples of Info Drop include:

Anime and Manga

In the anime adaptation of Full Metal Panic!, Chidori mentions that she's an orphan when bitch-slapping a captured enemy. "Oh, you've got no parents? Well, same for me and Sargent Sagura over here." Up until that point, it's not explicitly stated that her parents are dead, and the statement goes a long way toward explaining her character (and current living conditions).
One Piece thrives on this. Often tidbits mentioned in passing are revealed to have enormous significance. Eiichiro Oda's usual ploy is to have something relevant to the current arc, only to expand upon it at a later time. Continuity Porn contains one of the most major examples of this.
Mahou Sensei Negima has what appears to be a joke from one of the characters (later revealed as the arc's Big Bad) when she claims to be from Mars. Yeah, turns out that it wasn't a joke.
Gundam 0080 and Gundam ZZ provide Info Drops for fans trying to figure out when exactly the Universal Century takes place. The former has a newspaper that reads "Monday, 14 January 0080", while the latter has Axis proclaim itself Neo Zeon on February 29 0088, which means 0080 is a leap year in which January 14 falls on a Monday. The original series and Zeta Gundam both suggested that the calendar changeover happened in 2000, but these pieces of information were quietly retconned out in the Compilation Movie versions.

Film

In the movie of Fantastic Mr. Fox, there is much fun had with the conversion between fox years and human years (a 6:1 ratio), though a specific year for the movie's events is never given: it can, however, be extrapolated from Ash's age, Mr. Fox's age and the years we see on a trophy (1973, in case you were wondering).
The protagonist of Kill Bill is usually known only as the Bride, but there are hints and one specific scene that reveal it to be Beatrix Kiddo.
In the film of No Country for Old Men the date is only revealed from the fact that a 1958 coin "has traveled 22 years to get here".
While the film version of Watchmen pretty much makes Ozymandias as Ambiguously Gay as possible, the real proof comes from a desktop icon labeled "Boys" on his computer.
The Iron Giant makes no mention of what happened to Hogarth's dad, but during Hogarth's standoff with Kent, a picture of a fighter pilot is seen on his nightstand, and the audience is left to fill in the blanks.

Literature

One of the most famous info drops in recent years would be the dates on James and Lily Potter's grave in Harry Potter and the Deathly Hallows. With this information in hand, it's easy to figure out when the books take place (although it also makes the fourth book's claim of Dudley having a PlayStation highly dubious).
- The Harry Potter dates have been known since at least Chamber of Secrets, which celebrates the 500th deathday of N.H. Nick, who died in 1492. Also Rowling already admitted that the Playstation thing was written without verifying when was it launched or anything, not that it matters on the long run.
In the Circle of Three series, the coven that the Crones' Circle store owners belong to goes unnamed until the last book.
The only mention of Mr. Darcy's first name in Pride and Prejudice is at the end of one letter.

Web Comics

In El Goonish Shive, Sarah's last name was revealed in this manner; the principle used it to refer to her while rebuking her for breaking the dress code. The name? Brown.
This was standard practice in the early run of the Web Comic Gunnerkrigg Court. At the end of each chapter was a bonus page, giving details of the school and surrounding areas.

Web Original

In the Strong Bad Email the chair, Strong Bad taunts the audience by randomly pulling out a supposed picture of his parents, which is almost completely obscured by the screen-filling back of his new chair. However, decompiling the Flash reveals nothing on the photo but the message "nice try dodongo!"