Scenes that make you go Hmmmm

[claws]

... because you don't fully understand.

My favorite Hmmmm scene can be found in Brian De Palma's Dressed to Kill (1980). When Angie Dickinson's character is about to enter the building with the guy she just met at the museum. In said scene she steps out of the cab and turns to the left not once but twice, with a slight worried look on her face. We see a big truck backing up and the doorman of the building trying to help.
I guess that scene was left open to make your own conclusions but it always makes me wonder what was up with that.

[Jack]

Can't really think of a "Hmmmmm" moment, best I've got is a bunch of "WTF?" moments 

Like the end of Safety in Numbers (2006).

SPOILERS

So it's a slasher movie set on a tropical island.  By the end, we see our two survivors on a yacht headed for safety, and the killer, badly injured, walking on the beach.  So obviously they've escaped him, right?  But there's a second killer on the yacht.  At absolutely no point in the movie did they ever hint that there was a second killer, there was no explanation whatsoever;  it was just some stupid twist they tacked on at the end that made no sense at all.  I went over to IMDb thinking somebody on the message boards might have an explanation, but no - everyone is just as confused as me.

[Venomx73]

That makes me go 'Hmmmm'? How about EVERY scene in Super Mario Bros (1993) the movie.