This movie shows how much more harsh the MPAA has become toward nudity in recent years. Not even sex, mind you, just nudity.
The opening scene: a young singer wakes up to find an angry creditor banging on the door of his motel room. Both he and the girl with him are naked. She is passed out, so he throws her in the shower to wake her up. He hides behind the door as the creditor barges in and runs outside. The creditor pulls back the shower curtain to reveal the girl standing their dumbfounded. When she tries to escape wearing only a towel, the guy grabs the towel and pulls it off her, forcing her to run away naked.
Both the actor (Dennis Quaid) and actress (not sure) in this scene are completely naked throughout, both even showing some lower frontal nudity. And yet this movie was rated PG.
Why? Because the nudity in question was not sexual in nature and was played for laughs. Plus, at the time, parents actually understood that PG meant "parental guidance," i.e. it's up to parents to decide whether or not a movie is appropriate for their kids.
These days I think most people think PG means "ok for kids." It means, probably ok for kids but it's up to parents to decide that. It's not movie theaters or video stores responsibility to keep tabs on what kids are watching.