Here, you can see the absolute difference in the monitor covers from the rest of the episodes. In several 3rd season episodes, these different ones were used. In "Two Weeks in Space", the opening of the episodes shows John and Don at a computer that has one of the other monitor covers, and the other is in the Alien spaceship. My monitor cover is also seen in "The Haunted Lighthouse" and many others. The third season supposedly was filmed out of sequence which may account for the inconsistency in the monitor covers.