Here's the fun part of being an ASM. I'm running SR, and just before going onstage, an actor put down a prop on the prop table, then made his entrance SR. It's one of those specific props used in the show - like Desdemona's handkerchief. I thought, "that's not right, is it?" He exits SL and re-enters SL a minute later, so I didn't think he would want to crossover just to get this prop. I double-checked with the SL stage manager, and it didn't make any sense to her either. So, I walked over to SL with his prop and handed it to him - and was thanked profusely! He had just spaced for a second and thought he was done with it. It was the second show of a two-show day, and he got confused. He would have been really struggling if he had gone on without it.
It's just so rare to be thanked by an actor - during a performance, even! - that I wanted to mention it here.