When John and Don decide to leave the ship after it has landed in the space probe, they are on the upper deck. They go through the doorway to the left of the ladder and elevator, and around behind them. In the next shot they come out on the lower deck from behind the elevator on the right. Obviously they didn't use either the elevator or the ladder, so how many different ways are there to go between the decks?
When Dr. Smith opens the door to the Space Pod bay, the door goes straight up into the ceiling. But there shouldn't be anywhere for the door to go, since they are on the upper deck of the ship.
The events of this episode take place on Saturday, October 17, 1947. However, that date was a Friday, not a Saturday.