Frank the Pug (voiced by Tim Blaney) and the Worm Guys (voiced by Thom Fountain) are the only characters from Men in Black (1997) and Men in Black II (2002) to also physically appear in this one. Although they have a prominent place on the movie's poster, these characters have less than a minute of screentime.

After H and M land in the Merzouga desert after H hits the "red button" acceleration on the hover bike, they somehow manage to start a campfire, despite the area being devoid of vegetation.

Columbia ("The Torch Lady" in the Columbia Pictures logo) dons a pair of Men in Black sunglasses.

In the scene when Molly arrives at MIB headquarters in London, celebrity cameos appearing on the big screen varied depending on the country where the film was being shown. For the UK version Piers Morgan appeared and in the Spanish version, the YouTuber "Rubén Doblas Gundersen".

Featured in Good Morning Britain: Episode dated 26 April 2019 (2019)