I knew you are going to talk about that movie lol, the entire premises of the movie is based on literally everyone at the resort failing to do their job, and false facts.

It's literally impossible to happen unless you try hard (i.e. sneak onto the lift after they close). But even if it does, just climb on the lift cable onto the next tower, then use the ladder to get down.

As far as signal goes, whistle, flashlight, and cellphone are my regular ski gear, always on my person.