During Roger's last-minute party, as he's trying to get a tray of snacks poolside, he turns back to the house to answer the phone. When he gets to the answering machine, the ringing stops and Francis immediately starts leaving her message, which omits the prerecorded outgoing message that should have played (as heard in a later scene when Phillip calls from Vietnam).
During the "teenage party", Greenberg decides to change the music on the CD player and inserts "Rio" by Duran Duran. He only presses three times the "next song" button and should therefore reach the song #4 ("Hungry Like The Wolf"). Instead, it is "The Chauffeur" (song #9 on the CD) that can be heard, to everybody's dismay.
In the party/coke scene two hipsters take off Duran Duran and put on the Drunks With Guns song "Wonderful Subdivision" - and though the contract said the film would use "up to 40 seconds of the song" in the final edit only the first 4 measures of the drum intro are used, making it one of film's most expensive ($6000) "throw away" song edits. The DWG were probably St Louis' most infamous 1980's post punk band, lead by known felon & admitted misanthrope Mike Doskocil.
In the final scene just after Roger received the second doll he walks screen right. As the camera pans with his movement, it appears as though the camera is visible in the bathroom mirror at the back of the scene.
One of the complaint letters Greenberg sends has an address on "Eigth" Avenue.
The clothes worn by Greenberg, Florence and Ivan in some scenes include sweaters and jackets that would normally be too warm for Los Angeles, especially when some other characters are wearing swimming gear.