Harry Burns: How long do you like to be held after sex? All night, right? See, that's your problem. Somewhere between 30 seconds and all night is your problem.
Sally Albright: I don't have a problem.
Harry Burns: Yes, you do.
During the first car ride scene Harry is spitting the seeds out the window. One of the shots shown of the car from the outside shows the window still up after he has rolled it down.
In the famous faked orgasm scene, the woman who says, "I'll have what she's having. . ." is Rob Reiner's mother.