YMMV: Arsenic and Old Lace
- Hilarious in Hindsight: Baseball on Halloween!
- A combination of this, Harsher in Hindsight, and History Marches On comes with Mortimer's comment about how one of his ancestors "scalped the Indians" as proof of how crazy he was...in fact, historically whites DID scalp Indians throughout the various conflicts between them. Actually, scalping was invented by Whites (though some Indians did practice it on each other afterwards). However, since most white Americans didn't know these facts when the movie takes place, it doesn't break the Suspension of Disbelief for the audience when Mortimer tells this story to Elaine.
- Memetic Mutation: Jonathan's most elaborate torture method ("Not the Melbourne method!") has attained a small fame of its own. As of 2010, it is the name of an album by the Mabuses and a business - the latter is even located in Melbourne, Australia.
- Nightmare Fuel: Jonathan. The fact that he's in a film where everyone else is just charmingly kooky makes for quite a contrast.