On a sufficently wide enough screen the "Why are you rejecting this edit?" popup can be triggered to open multiple times when the "Reject" button isn't fully covered by it.
I just noticed this when (*ducks*) double-clicking the "Reject" button then rejecting a suggested edit in the second pop-up. My vote was accepted and the second pop-up closed to reveal its predecessor (the first one).
Although not a major issue, I'd suggest temporarily disabling the buttons after the pop-up is displayed or showing the pop-up over a faded out layer (e.g. a 50% opacity <div>, making a second involuntary click unpossible).
