During the conversation between Dr Carrol and the man from the FBI, there is mention of a case involving a young woman found in the company of five men. The FBI man introduces the case as being from Michigan, then later says that it took place in West Virginia.
The same art deco ashtray that Mae Coleman has on top her piano (as well as the piano) also appear in the famous "Play Faster!" scene (where Ralph is in hiding from the cops and the girl plays piano for him while he's high).
When Dr. Caroll and the unnamed man behind the desk talk about marijuana, there is a door by the filing cabinet that has had a name removed from it (not done very well). In a later scene with Dr. Caroll and Bill, the same door appears next to bill. (Both scenes filmed on same set.)