When Vince, Eric and Ari meet with the president of Warner Brothers, Vince calls him "John" (saying "I'm all about family, John.") The president character has always been named "Allen".
In the lunch scene with the boys, Shauna and Marvin, a blond in a red dress and a brunette with a purse walk behind Drama. In the next shot the same two girls walk behind Turtle, who is sitting to Drama's left. In actuality the girls should have been out of sight, walking behind Drama's right.
Warner Brothers president Allen Grey says Clint Eastwood has been with the studio for 70 years but Eastwood was only 74 at the time and didn't start acting until he was 25. He didn't act in a Warner Brothers film until 1971.