I keep seeing guys at work dumping rounds everywhere because they bump something with the butt of the gun.
I've seen people do that with a Glock +2 extension as well. But then I examine the mag in question and see they didn't install the magazine insert. The +2 is actually both those pieces used together. The insert locks the baseplate in place. Without it.... things can go wrong quite easily.
Look at the Glock factory 33 round 9mm mag. Ever see anybody knock the extension off it and spill the rounds? Me either. And I assume that is because the 33 round mag comes with the +2 already installed. Properly!