On the way out you have to play with the lanterns again, including the one in the side room, IIRC. I know I did have more trouble getting out than in, but after playing a bit, figured it out.
One person got into the house by tossing a teleporter into the window, so could not get the lanterns in the correct order to exit. They had to leave via the window again, then enter the house through the front door to trigger the final cut scene with Elrath.