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.
The MiB Agents have been wearing the same standard issue Hamilton Ventura watch since the beginning. The iconic Ventura watch was first released in 1957.
There is a secret apartment at the top of the Eiffel Tower where Gustave Eiffel entertained famous guests like Thomas Edison.
Tessa Thompson loves the character of Pawny and knew that Kumail Nanjiani would be perfect for the role. Although his character is all CGI, Nanjiani flew out to London so he could read with Thompson and Chris Hemsworth in person, making the character interactions feel more dynamic.
Sir Paul Smith, who helped design the suits for the MiB Agents in this movie, appears as the typewriter repairman at the secret entrance to London's MiB Headquarters.