Continuity mistake: When Alex tells Jennifer to play her clarinet outside Jennifer complains that its dark out, but you can see through the window that it is bright out. When they show it again it is dark.
Character mistake: When Uncle Ned calls Alcoholics Anonymous, he only dials 6 digits on the phone (instead of 7), but still the call successfully goes through.
Answer: Since they don't have a door there in the living room but they do have a door there in the dining room I assume it leads to the dinning room and the door upstage is probably straight to the living room while the door downstage goes to the dinning room and then through more doors you get to the door in the the living room. Hope that made sense.