Ed, the chimp, is actually "just a guy in a suit" (according to Matt Leblanc), with a mechanically controlled head. That head made so much noise that all the dialogue in the scenes which included the "chimp" had to be re-dubbed in post-production.
Ed watches an episode of Friends (1994), the show that made Matt LeBlanc a star. The scene he watches features Marcel, the pet monkey of one of the characters. He appeared in the first 2 seasons, and his story-lines were similar to the one in this movie.
Adam Sandler was offered the lead role but turned it down to make Billy Madison
Texas Rangers second baseman Mark McLemore, long time friend of Matt LeBlanc, spent time during off season teaching LeBlanc how to look and play like a major league baseball player.