He can't be a zombie if he shot himself in the head whilst he was still human. The only way to KILL a zombie is to headshot/decapitate.
Everyone knows that.
I thought this scene looked great until undead Chaplin rose up
The way you've bought in Hitler as a zombie just seems like it's for lols and shock value (which kind of feels a little immature and clichéd, now) and for no other discernable reason. I think that's what's off about it.
That being said, the art is very nicely done. The first shot of the chair blew me away, tbh.