Oops; my goof about the indicators for the digital ads system. I know the panel you're talking about. Some of the theatres i worked at had them and some didn't. What I was talking about was a little black box with a reset button and a multicolored LED on it that wired into the computer that controlled the digital projector. The computer was also wired into the automation system. The reset button would manually restart the stack of ads running. And the LED would flash green when it was time to start the projector. It would flash red if the projector had not been started yet or there was a problem.
I can say for sure that I never ever ran the wrong movie. Accidentally started to thread the wrong one a few times; bur never started the wrong one. I did have a new projectionist start the wrong movie once. She freaked out when she discovered it. It amazes me that some people can't figure out what to do. Luckily it was still in the previews, so I had her run it down to where the next preview was about to come off of the platter. She stopped it and I broke the splice and had her run the film through the projector and onto the take-up platter. Then I took the center ring with the film off and had her thread up and start the proper film. I don't know what you guys call it over there but I did what we called a center-drop. That's were I take the center ring with the film and place it on top of the rest of the print on the feed-out platter. Then I carefully cut out the torn splice and resplice the film. Then gently pull the center ring out and work the film into the middle of the feed-out platter; forming small loops if neccessary. I was about the only one who could do it successfully every time, and I could do it with up to about a reel's worth of film. I've done it with more but it can look like a mess.
I did have another new projectionist who started the wrong movie. After he discovered his mistake he didn't bother to stop it. At least he came and got me. When I got to the projector and saw it still running I asked "Why didn't you stop it?" His reply was "I don't know." He didn't last long.