The guy sitting at the $100 table is Vince Vaughn's father and the old lady who wins Black Jack is Jon Favreau's grandmother.

The girl on the answering machine who says "Did she call yet? I'm sure she...." is Heather Graham's voice (the girl Mike meets at the end of the film).

The last scene of the movie, where Trent sees a woman who he thinks is making faces at him when she's really looking at her baby, was taken from an actual event that happened to Vince Vaughn in an airport, only it was with a man (and Vaughn was freaked out by it, not playing along like in the film.).