Continuity mistake: In the episode "First Kiss," Justin has a girlfriend, Miranda. But in this episode Justin starts dating this new girl from his class, who's actually the same Miranda. This doesn't make any sense. How is she a new student and how could they just meet if they were dating eight episodes ago?
Continuity mistake: In 3-7 "Employee of the Month", Joe Christie says he was with Monk when he got the news of Trudy's death. He said Monk had been laughing, and that he never heard him laugh again. In this episode Monk and Stottlemeyer get called to the scene of a crime, a women's clinic. In this episode there is a flashback to the exact same location years earlier and to Stottlemeyer getting the phone call about Trudy's death. He and Monk were working a case that day and Joe Christie was not present.
Continuity mistake: Lily and Marshall mention that they've been using the same toothbrush ever since they've been together, but in the 14th episode of the 1st season, "Zip, Zip, Zip", Marshall and Lily are simultaneously brushing their teeth with a tooth brush each (before Ted and Victoria get home). (00:05:05)
Continuity mistake: In episode 10 (Joey's Place) the Tanner family move Joey into the garage, redecorating it so the entire place is filled with Joey's furniture, but in this episode it shows the characters in and out of the garage which is completely empty and back the way it was before Joey moved in. Later in the episode Joey's stuff is out of the alcove again.
Continuity mistake: When Rachel finds out that Ross and Julie are getting a cat, watch Rachel's neck. When she says "together?" she's not wearing a necklace; cut to Ross and Julie for a fraction of a second, then when it cuts back to Rachel saying "both of you?" she's suddenly wearing a necklace. It then disappears again when she says "isn't that just lovely?" hanging off the side of the tray she's holding. (00:05:15)
Continuity mistake: When Phoebe is left alone at the couch, her mom comes up to talk to her. Before her mom shows up, there is a water bottle in front of Phoebe. After Phoebe's mom sits down next to her, the water bottle moves to the other side of the table without anyone touching it.
Continuity mistake: When Kitty comes downstairs to give the gang cookies, she tells Eric that she picked out an outfit for him to wear on career day. He then turns and mouths the words "Help me." In the next shot you can see Jackie sitting on Kelso's lap when in the previous episode, she broke up with him. In the next shot she is standing behind him. (00:01:00)
Continuity mistake: Steve receives a Rowflux and five containers of protein powder. He takes one of the containers leaving only four still on the floor. In a subsequent scene, Steve is still holding the container but now five containers can be seen behind him, giving him six containers altogether.
Continuity mistake: When Howard is almost done moving out of his mother's house, there is a table in front of him with a measuring device in the top corner. In one shot, the device moves to the opposite corner of the table. In a few shots later, the item returns to its original position.
Continuity mistake: In the scene explaining the history of the missing jade elephants, they are described as being given to ambassadors by the emperor Zhu Di of China when the Forbidden City (in China) was first opened to foreigners in 1421. When the elephants are all brought together, the representative Daichi Yoshida from the Japanese embassy comes to pick them up, describing them as "a priceless piece of our history."