Though we see the movie through the eyes of the time traveler as he bounces through the evening in 11-minute increments, the movie was shot in the order of the wedding reception. This was done for continuity reasons. If something spilled or broke early in the evening, it had to be seen in the scenes the audience would see first.
In addition to all the other reference to where we are in time (the time maps proceeeding each scene, the digitial time stamp of the "hidden" camera,) it's possible to track the time each sequence takes place by watching the state of the helium balloons attached to the lattice.
The only actor who had to keep track of where he was in time was Ian Michaels who plays the time traveler.