Ritter/Camp and O'Neal/Kahn
First let me just say I LOVE this movie, saw it for the first time last month and it's a marvelous motion picture.
That said, did anyone else, while they were watching this, get the weird sensation when they watching John Ritter and Colleen Camp's interaction (Who I think steal the movie, btw) that Bogdanovich pretty obviously ripped their relationship and the way they behave with each other from that of Ryan O'Neal and Madeline Kahn in "What's Up Doc?" (an equally great film). Even though O'Neal and Kahn were married in "What's Up Doc?" and Ritter and Camp aren't in "They All Laughed", you still get that "incredibly shrill, constantly nagging, drive a man crazy if they weren't somewhat dead inside" thing going on. And coincidentally, O'Neal's character's name in "What's Up Doc?" is "Harold", which is the name of Camp's cat in "They All Laughed". And when Camp talks to her cat, she sounds like Madeline Kahn.
"Mein Fuhrer, I Can Walk" -- Dr. Strangelove