I like the idea of Obi-Wan destroying things and causing trouble when he's shutting down the tractor beam. He could blow up things and kill people from both trilogies such as:

1. Blowing up Alderaan (that would mean that the shot of the Millenium Falcon arriving at the remains of Alderaan would have to be skipped past to the shot of the Falcon approaching the Death Star--it could be used later though, showing that Obi-Wan was oblivious to the destruction he was causing--and the scene where Tarkin orders the destruction of Alderaan would have to be skipped as well)...

2. Starting the trash compacter (this has already been suggested)...

3. Causing explosions throughout the Death Star (using shots from attack scenes on both Death Stars)...

4. Causing the Super Star destroyer from Episode VI to crash into the Death Star...

and

5. Blowing up the Death Star (which would have to be followed by an "OOPS!"--if you can find or make one--and a rewind of the Death Star explosion).