Done for effect in many movies, just before Kitty shoots Jimmy, a "cocking the hammer" sound can be heard. Glock handguns don't have an external hammer.
When Nick opens the suitcase of money, the serial numbers of the $100 bills are all the same: B04586335F.
The waitress tells Nick she is from Potato Creek Indiana. Potato Creek is a State Park and as such, no one lives there.