The theater only had one showing of FotR at 9:25pm. I had called ahead and the manager-on-duty had said the preview would be showing. About half of the seats were filled.

About 15 minutes before the end of the movie, I saw an Eagan city police officer come in with a dim flashlight and kind of check out the theater. He then proceeded to stand in the entry way for the rest of the movie. I figured that he was there to stop people from sneaking in from other movies just to see the preview.

As the last scene of FOTR ended, the theater lights came on and the between-films advertising track started playing. There were no credits or anything. This kind of irritated everyone and there was some grumbling. A few people left, but most stayed even though there was no indication about what was going to happen.

After about 3 minutes of everyone trying to figure out if they were going to show it or not, the cop finally shouted "If anyone wants to stay for the trailer, I have someone checking the projector right now." That was all he said. After about 3 more minutes, the lights suddenly went down and the trailer started. It started pretty abruptly and sputtered for the first couple of seconds. However, based on what I have read on the net, I think we got pretty much the whole thing and the FotR credits followed the preview.