Happy Birthday... Everybody - S3-E20
Plot hole: After a chance meeting in Mexico, Tom Matthews invites Kelly and Scott to his home for dinner. The address is unlisted, neither knows where the other lives or is staying, and no address or phone information is exchanged before they part. But Kelly and Scott somehow find the house anyway. (00:09:50)
The Marathon - S4-E3
Plot hole: Jason cheated in three different ways in order to beat Aurelius in The Marathon, and admitted it. So the bet that they made between them is null and void. But the last shot shows them living up to the terms, which includes Aurelius starting to eat his own shit (literally), so revolted that he's trembling. Apparently the writers really really wanted to include coprophagy. But who would eat faeces for a bet, if you can simply avoid it by reminding your opponent that he cheated? Or even better, many would say that cheating means losing automatically, so he's the one who should be eating his own shit.
Plot hole: Rick is taking care of his girlfriend's goat for a few days. He puts a bowl of milk on the floor, but The Goat will not drink. Harriet suggests, "We're probably just using the wrong method." The next scene shows Ozzie at the stove, heating milk in a baby bottle. Rick is 22 years old. Why would Ozzie and Harriet still have a baby bottle in the house?
Plot hole: Someone as careful and controlling as Timo would never force anyone into working for him, for exactly this reason.
Farewell My Beloved Witch - S1-E3
Plot hole: Lupin was captured by chance, and he did not plan for that, nor he seemed to have previous knowledge of Stern's appearance, but he escapes regardless using a Mission Impossible-like perfect mask of him. He also somehow kept his own blazer, tie and shoes underneath the uniform and boots he stole and wore. (00:16:00)
The New Kid - S2-E7
Plot hole: In the season two episode 'The New Kid,' Daria and Jane are discussing The New Kid in gym class when a girl takes a nasty spill from a trampoline. Later, Daria and The New Kid are heard remarking about photos taken of that particular fall despite there having been no photographers present.
Plot hole: In the pilot, it is established that the surface of anything/anyone made invisible by "quicksilver" is freezing. (Darien gets caught in the women's shower because the mist freezes on him. He freezes the beer mugs for the doctors.) But in later episodes, nobody notices him standing invisible - and freezing!? - next to them.
Plot hole: The bad guy somehow knows what is going to happen (via the sketches) even though the events haven't happened yet, like knowing Mrs Peel was going to show up at Pool's mansion in that catsuit and hat, and that the scenes were going to play out like the sketches.