[About Troy's trap]

What I don't understand is how the hell Jigsaw could have done all this. He was damn near on his deathbed last time we saw him.

I'm not so sure he did. So far, this doesn't fit his pattern.

Meaning?

Well, how did you get in here?

We cut the door down.

Why?

Because somebody heard an explosion and called us.

I mean, why did you have to cut the door down?

It was welded shut. Bloody truck couldn't get through there.

Exactly.

I don't follow.

If the aim of Jigsaw's game was to escape the room before the bomb went off, then why was the door welded shut? Guy couldn't get out even if he wanted to.