Just a little thing that's bugged me since I saw Saw 2.

In the scene where the man climbs into the crematorium, you may notice that there's a large glass window there. Problem is, in order to incinerate a human body, it requires around 2000 degrees farenheit. (I forget the Celcuis temp)

Glass melts at around 1500 degrees. Meaning that it'd be physically impossible for them to have a glass door on a crematorium.