In response to Sandra's review, I was at the understudy show as a parent and have a completely different take. The kids loved that the director came in and the actor whose line they took was completely aware because the director came in at the time the usual actor does. The actor then came in from a completely different spot. I would imagine the rest of the cast was not uneasy but instead trying hard not to laugh. These kids had begged the director to do the whole part and he said no. This quick change was done in response to their begging.
The second scene was also a quick dance in a circle with other cast members and was not dangerous. It was just enough for the audience to realize it was a joke and then they left. My daughter loved these two parts that were done for the understudy show and the kids realize anything can happen. The kids don't necessarily get a full run through but that happens at most places with understudies. Sometimes you get to have a run through but not always. The lifts were actually done by a lot of the same cast. One actor actually came in just for the lift because he did it when he was his main role.
The track was definitely legally purchased when they bought the rights. The play stops and gos with music because that is what it does. There was nothing wrong with this performance and my daughter and I loved it