A bit late to the party, but hopefully I can still add a thing or so...
...it is difficult to watch Wrestling with Shadows without at least some sense that the whole thing was set up. It's incredible timing for the documentary filmmaker, and certainly a brilliant response from McMahon. The creation of the McMahon character seems largely to have made Steve Austin who he is.
Was it all set up in advance? Was Bret playing along? Well, my feeling is, if not, he probably should have. The "reasonable creative control" mentioned in one of Joshua's posts should have been a red flag as to the kind of business he was in. Not wanting to lose in Montreal because it's his hometown? Leaving aside that his hometown was technically in a different province, what reasonable person, having worked for McMahon, would expect to have much pull in an angle as carefully worked out as Bret v. Shawn. And that Vince would let him win the match, trusting that he would turn over the belt after (despite the problems that always seem to occur when a champion leaves)? There's a joke in High Fidelity about asking for a dollar, getting turned down and then asking same person for 50 grand, and it seems appropriate here. Bret was an employee, and should have expected something was up when McMahon agreed to negotiate with him in the slightest.
After all, as J.R. said, there's not always a lot of difference between Vince and Mr. McMahon.