Trivia: The film features a cameo from Frank the pug, who appeared in the first two films, but was absent from "Men in Black 3." Oddly enough, despite only appearing in the film for a few seconds, Frank appears quite prominently on several posters and even on the DVD cover art for the film. (The same is true for the "worm guys," who also appear on posters and the DVD cover despite only having a brief cameo in the film).
Trivia: Early in pre-production, the film was going to be a humorous crossover between the "Men in Black" and "21 Jump Street" film franchises, featuring Channing Tatum and Jonah Hill having to go undercover in MIB. The working title was "MIB - 23." The idea was dropped, presumably due to its outlandishness.