Plot hole: Even though he knows the FBI is looking for him, the Punisher shows up at Agent Donatelli's funeral (which is being attended by many FBI agents) in broad daylight. This is completely out of character for someone who will go as far as living in the sewer to avoid capture.
Add timeSerious B
Other mistake: In the standoff scene at the end between Castle, Jigsaw and Loony Jim, Castle enters with a fancy revolver that the Jigsaw takes, checks out and then shoots Castle two times and then gives back to play Russian roulette with. That revolver is a modified Smith & Wesson 500 and it would leave a hole a good deal larger than what is shown, they are so powerful in fact they can go through solid cement block.
Other mistake: In the dinner shootout scene, The Punisher hangs from a chandelier upside down using his legs, and starts shooting people while spinning for about 20 seconds, but there is no apparent force which makes him spin so much in the first place; he doesn't even make a "first turn" with his body in order to start spinning.