Smith, hamming it up, refers to "that bourn from which no traveler returns". It is impressive how often that line from Hamlet Act 3 Scene 1 is misquoted. It is from the 'to be or not to be' soliloquy, "...death, the undiscovered country from whose bourn no traveler returns..."
As John and Maureen, using the chariot, continue searching for Will, the Robot is riding in the back seat. As the inside of the chariot is not tall enough for the Robot to stand up in, only its top half is visible.
This is the first episode where John Robinson is referred to as "Professor" Robinson. In the previous early episodes he was referred to as "Doctor" Robinson.
This is the only episode in which Maureen refers to the Jonathan Harris character as "Smith," without putting the "Doctor" before his name.
The first of two episodes where Don flies the jet-pack. The other episode where he does so is "The Raft"