It wasn't always Meg Ryan and Billy Crystal. Lots of other actors were considered for the roles, including Albert Brooks and Molly Ringwald. And may we just say? That would have been a weird combo. (Source.)

If you visit Katz's Deli in NYC—the site of the infamous you-know-what scene—you can sit in Harry and Sally's booth underneath this sign.

Billy Crystal is known for his improv, so it makes sense that he threw some into the movie. Our favorite moment? He improvised the line "But I would be proud to partake of your pecan pie." You can tell because Meg Ryan laughs spontaneously and briefly looks off camera to Reiner, who encouraged her to go along with the scene. (Source.)