- Dueling Movies: With Lilo & Stitch and The Powerpuff Girls Movie. It shared similarities with the former for having an alien posing as a dog, a reference to an iconic "King" of music, and the fact that the films had to be altered due to 9/11. The similarities with the latter take place in a city, except in this film, it didn't go through Scenery Gorn. It clearly won the box office over the two but not critically.
- Edited for Syndication: The brief "He's a Ballchinian" scene is typically edited whenever it appears on TV. Instead, J says "He's a Chinnychinian" and K grabs his scarf but doesn't pull it off (thus leaving his chin testicles covered) before kicking him, removing the punchline.
- The Other Marty: Famke Janssen was originally cast as Serleena, and completed some scenes before dropping out due to a death in the family, with the role subsequently recast with Lara Flynn Boyle.
- Technology Marches On: Kids who grew up with DVDs and digitally downloaded movies probably won't get the locker-aliens' "Be Kind, Rewind" reference. The "Adult section in rear" gag, teens can probably figure out, though it also dates the picture.
- Throw It In!:
- Will Smith's line when showing Kay the car: "Actually it came with a black dude, but he kept getting pulled over". Apparently they reused it so much that he soon became sick of it.
- Rapper Biz Markie was visiting Will Smith on the set and they were beatboxing to each other. Sonnenfeld saw this, loved it, put Markie in as an alien in the post office scene, and added the part where J speaks to him in his native language (which was really just their beatbox routine).
- "He's a Ballchinian!" Other takes identified him as a Gonadineck, Nutchinian, Chinball, Nutthroatean, and Chinsackian. Another way of pointing out the weakness was "He's got a scrote-tee!"
- The moment where Serleena sticks her tongue in K's ear was an improv by Lara Flynn Boyle in an attempt to make Tommy Lee Jones break character. It didn't work.
- Typecasting: Michael Bailey Smith plays the mugger at the beginning who attempts to sexually assult a recently supermodel-fied Serleena, only for her turn the tables and swallow him whole. Three years earlier, he played a security guard who gets eaten by a transformed Lizzie in My Favorite Martian. Making him possibly the only person ever typecast as "man who gets eaten by a transformed alien woman."
- Wag the Director:
- According to the book The Man Behind the Mask (a biography without Jackson's involvement so it should be taken with a grain of salt), Michael Jackson would have appeared in the sequel for free... if Will Smith were dropped from the film so he could be the protagonist. He couldn't convince Sony's higher-ups that this was a good idea, hence the cameo instead.
- Even after agreeing to his cameo, Jackson wanted the movie poster to feature him in the center between K and J, and covering as much space as the two.
- What Could Have Been:
- The movie would've used the World Trade Center in some way, but then September 11th happened.
- The first filmed ending revealed that K's locker at the station was not a miniature world but actually an optic portal to another planet and that the furry aliens in it were actually gigantic compared to humans. This would be shown by K playing a prank on J, which consisted on J being given a ride in a flying saucer under the belief he was being taken to visit Laura, but being sent to the furry alien planet instead. At the very end, K would look at J from outside the locker and close the door.
- Halle Berry, Jennifer Lopez and Yeardley Smith originally auditioned for the part of Serleena.
- Robert Downey Jr. and Keanu Reeves auditioned for Scrad and Charlie.
Trivia / Men in Black II