The Wedding - S5-E11
Plot hole: In the episode "There Goes the Bride," Haji warns Jeannie that she will lose her powers if she marries Tony. Yet, she marries him in this episode and does not lose her powers.
Plot hole: The Jupiter 2 crew is duplicated; however, the aliens had never seen Penny (or Judy I think). How can they be duplicated? The aliens don't have ability to know who were there, or they wouldn't have questioned Smith about the crew. Also, they do not know Smith and Will are hiding. So, they don't arm to have any special power to know beyond what they actually observe.