An extremely infuriating one that repeatedly gets me because I forget about it: the AM/PM wheel when setting an iOS alarm. If I set an alarm the night before and the last thing I do is flick the wheel to AM, but then hit save before the animation has finished it's very subtle and slight easing/bouncing animation, the setting remains at its original value (PM because I'm creating the alarm at night) and thus the alarm does not go off in the morning when I expected it to.

You're right, that one drives me nuts. Any slide wheel doesn't change its underlying value until it stops animating, even if it's 99% of the way there. You navigate away from the screen thinking the new value is set, but it's not.

That one falls into the category of UX felony as far as I'm concerned. It's not just delay or confusion, but actively misrepresenting a value.