Susan: Arthur, a real woman could stop you outside from drinking...
Arthur: Yeah, but she'd have to be a real BIG woman!
When Arthur is in the bath tub, Hobson brings him a martini on a tray. Arthur grabs the glass. It shoots over to Hobson then back to Arthur and he picks up the glass again without even putting it down.
John Belushi was the first choice to play Arthur. Belushi thought the script was excellent but he turned down the role as he had already played a hard-drinking guy in ‘Animal House', and feared being typecast as a substance abuser.