The onions that Stanley and Zero eat towards the end of the movie are actually apples wrapped in an edible cover.
Despite being billed first, Sigourney Weaver does not appear until approximately forty minutes into the film.
Dulé Hill played Sam. He later appeared as Shawn's (James Roday's) co-star, Gus, on the television show Psych (2006). In the episode "65 Million Years Off" when seeing all the holes that the paleontologist dug on the land, Shawn mentions "that this is like that movie with Sigourney Weaver". He also mentions Shia LaBeouf and Jon Voight. Gus keeps guessing movies, but never correctly guesses the movie that he appeared in, Holes (2003).
Louis Sachar: The author of the novel and the screenplay appeared with his wife and daughter in the scene where Sam is selling onion juice. His one line: "My head?"