When Ray and Claude are standing on a box of bottles, Claude mentions that a one of his toes has slipped into one of them. This actually happened during the take, but Martin Lawrence kept going, despite Eddie Murphy's laughing, which is genuine.
Spanky's (Rick James) limp was not acting. The scene was shot after Rick James underwent hip replacement surgery.
According to the DVD commentary: During the diner scene, originally it was Eddie Murphy's character that was supposed to be angry about the "White Only" pies, while Martin Lawrence's character just wanted to leave. During filming, the scene wasn't working, so they came up with the idea of having them switch their lines. The scene played much better and that's how it appears in the finished film.
When Rayford (Eddie Murphy) is getting beat up in a fight, he says: "I know a bitch named Della who hits harder than you." This is a reference to Harlem Nights (1989), in which Murphy's character is beat up in a fight with a madame played by Della Reese.
Of all the movies on which Eddie Murphy and makeup artist Rick Baker collaborated, Life (1999) is the only one where Murphy did not play more than one character. Baker only used the makeup to age Murphy's character in this movie.