The zombies can damage you even while you're in the shop. (At least you can reload while in the shop.)
The money counter is missing a digit; once I went over 999 I thought I went broke.
I died with an excess of money, like 3k (I guess? Maybe 2k, I'm not sure... cuz it's missing a digit.) By then, it was getting laggy with all the zombies.
When I died there was no indication of how much I achieved, niether how many I killed or how far I progressed.