Dyeing for Your Art: Parodied with Kirk having his skin dyed to become a sassy black sergeant. Alpa Chino, a real black man, is not amused.
Fake Nationality: American Robert Downey, Jr. played an Australian who was playing an African American and even disguised himself as an Asian farmer. He's a dude playing a dude playing as a dude disguised as another dude.
The Vietnamese cartel Chinese Dragon is lead by a Chinese-American and the second-in-command is Filipino-American.
Method Acting: Kirk Lazarus undergoes surgery for a better racial resemblance and doesn't drop from character until he's done with the DVD commentaries.
The Other Marty: Owen Wilson was originally set to play Tugg Speedman's agent, Rick Peck, but after his suicide attempt, he understandably backed out of the role. The role ended up going to Matthew McConaughey.
Playing Against Type: Tom Cruise in a fat suit and heavy make up that make him almost unrecognizable as a crass Jerk Ass film producer in a comedy film is probably one of the biggest examples of this trope in history.