The part after you leave the sewer is pretty damn glitchy, if you take the wrong door (which you can do through the fire) you can come into older versions of the area without enemies or fire. And even if you go into the right room where the ladder is, if you press the electronics on the wall you'll once again get the cutscene of you hiding as the red man clomps inside for a stroll. And if you shoot a zombie that's already been felled it stands up again for you to kill it allover again. Then during the final fight, the door you came out of was open but gave the message that it was locked =P
I hope you fix all these glitches so I can recommend the game to people, because the rest is pretty solid =)