Ben Stiller said nearly all aspects of the Les Grossman character were developed by Tom Cruise, including the dancing and the look of the make-up. Stiller said that in addition to the more obvious make-up effects applied to Cruise's face and head, and the extra hair on his chest and arms, Cruise also decided to play the character wearing oversized prosthetic hands.
In the film, Kirk Lazarus says, "I don't drop character 'til I've done the DVD commentary". When recording the audio commentary for the Unrated DVD and Blu-ray, Robert Downey, Jr. actually spends the entire commentary in the character that appears on the screen as the movie progresses. This line was cited when Downey was introduced at the 96th Oscar ceremony along with the other nominees for Best Supporting Actor. Downey, of course, then won for his role in Oppenheimer (2023).
Owen Wilson was originally set to play Rick Peck. After his attempted suicide, Ben Stiller gave the role to Matthew McConaughey so that Owen could relax.
The South East Asian gang Flaming Dragon, led by a pre-teen boy, was modeled after God's Army, a guerrilla army in Myanmar. The group was led by twin brothers Johnny Htoo and Luther Htoo, who were nine years old when it was founded in 1997. Johnny and Luther Htoo were fond of American action movie heroes, especially Rambo.
The water buffalo that Jack Black rides turned out to be pregnant. The cast and crew found out when they came to the set one morning and found her nursing a newborn calf.
Christine Taylor: Ben Stiller's wife appears at the awards ceremony, sitting a few chairs in from the aisle. She is briefly visible as the camera follows Tugg down the aisle. She also played Simple Jack's mother in the "Simple Jack" trailer.
Justin Theroux: During the party scene, following the video conference, Theroux can briefly be seen as his Evil D.J. character from Zoolander (2001).
Justin Theroux: The gunner on one of the Hueys in the beginning of the film. He also had another cameo in another Ben Stiller film, Zoolander (2001), as a DJ.