
Plot hole: There is no way that Zoey could've seen those boys hanging Chase's bike from a tree. She was way far from the window to even recognize his bike, and when Chase looks through the window, the bike was just now being lifted from the ground.

Mac is a Serial Killer - S3-E10
Plot hole: Early in the episode, it is mentioned that the serial killer is murdering "Young, attractive blondes", yet at the end of the episode, when the gang finds all the severed heads in the killer's refrigerator, almost none of them are blonde or young, contradicting what had been previously established.

Plot hole: Kenan ends up out of the door when trying to persuade the robbers not to give. Surely with all the media attention, a camera would have spotted him, and his family would realise it's Kenan. (00:20:30)

Plot hole: The bedroom scene finds Robert sitting up in bed after getting home from the hospital with his upper thigh injury. If he really had a wound in that spot, there's no way he could sit like that.

Plot hole: In Blakey's office Stan shows Blakey the toy bus he has just brought for his nephew. How can Stan have a nephew when he isn't married and his only sibling is his sister Olive, who doesn't have any children?

Oops!...I Did It Again - S2-E22
Plot hole: Lily was vomiting because of the antibiotics she was taking for the infected tattoo. But initially, Sean and Claudia were both puzzled by her being sick. As a teenager, how could she have seen a doctor and been prescribed medicine without a parent knowing?

Plot hole: When Justin and Juliet were trapped behind the glass and Juliet let herself be captured by the mummy, so she doesn't burn to ashes when the morning comes, why didn't Juliet just escape? The mummy gave her enough time to turn around and share a moment with Justin, she could've used that time to fight him off, break Justin out and escape. The mummy wasn't very strong and Alex would've shown up 20 seconds later anyway, there wasn't any real reason for Juliet to just let herself be taken away.

My Late Lamented Friend and Partner - S1-E1
Plot hole: When Jeff and Marty are parked, waiting for Sorrenson to exit the building opposite, Jeff says he should call the police. But he immediately follows Sorrenson and has no time to do so. Later, they arrive even though not called.

Plot hole: Amy lets Scully place the watch in the break-room, but how could she have known that after Captain Holt steals the crown out of the locker, he would go there? And not, for example, go back through the window he came from.

Plot hole: In this episode, a very star-struck Paul meets Jerry Seinfeld on the street. It's not clear whether Jerry is playing himself or his Seinfeld character, but either way it's a mistake. If Jerry was playing himself, it's a mistake because Mad About You did a crossover episode with Seinfeld in its first season, so it would be impossible for Seinfeld (the TV show) or Jerry Seinfeld the actor to exist in the Mad About You universe. If Jerry was playing his character, it's a mistake because it was established in that crossover that Paul and Jerry used to be neighbors and knew each other fairly well, so Paul wouldn't be at all star-struck.

Plot hole: During the episode "Superstition", Onizuka thinks he has cancer because the magnetic pain-pads he was wearing created strange blobs in the X-Ray he has taken. However, given the fact that the X-Ray was so strange, doctors would have given him a complete physical, and noticed the pads much sooner. Here, they literally just assume he has tumors, and fail to ever take notice of the pads. Simply impossible, given the gravity of the situation. (Obviously, this is to pay off at the very end of the episode.)

Plot hole: Doctor Yes' execution trap involves a booth flooding with water, drowning the occupant, and the water pushes a float upwards, eliminating another via a spinning blade. However, several times the float reaches the top of the booth, and the spinning blade doesn't kill anyone. There's also a breathing space at the top of the booth, so people couldn't drown in there.

A Scooby-Doo Valentine - S3-E3
Plot hole: It's never explained how JC Chasez and the Hollywood extras impersonating the gang gained the super strength they possessed to do things like ripping car roofs open or holding up the Mystery Machine.

Plot hole: When Connie uses the wish machine to make Malloy small again, she instead wished for Ethel's breasts to get significantly bigger. However, in the next scene Ethel's breasts are back to her regular size. The plot shows that the wish doesn't wear off, and someone else would have needed to wish for Ethel's breast to get smaller but no one did.

Circle Sewn With Fate / Unlock Thy Hidden Gate - S1-E2
Plot hole: Spoiler - considering what emerges at the ending of the series, Agatha's behaviour in this episode hardly makes sense. She had no trust in the Witches' road; in fact, she knew it did not exist at all, and her only aim was to steal the powers of the other four witches during a fake ritual. However, one of them is a normal human with no powers, one is a witch with her powers sealed and thus impossible to steal, and she literally tells the third one how her very specific energy-stealing power works - which, of course, is entirely absurd considering she had no purpose for her, given the lack of a real ritual.
Suggested correction: The whole point was to just get a witch to do the ritual. Agatha's earthly ability is to read people. Knowing it's a rouse, she tells Lillia what she needs to hear to participate in the ritual (the road will make Lillia more powerful) and that at the end of the road, Agatha cannot just steal her power. She knew she needed to show a bit of her hand and had no doubt a witch would blast her out of anger (and show no restraint) when the song was over and no door appeared (human nature).
Suggested correction: She made do with what she could find. Two of the witches had powers she could steal. Since she was totally powerless at that time, it would be enough for her. After taking the power of just one or two, she could have killed the others just as easily. It didn't matter to her that one of them was not a witch at all; she needed four to make them believe they were walking the witches' road.
"I can't steal your magic unless you blast me with it. So if you show a little self-restraint, which, let's be honest, you're gonna need to, all that power is yours to keep." This is not me paraphrasing her for humour or to be concise; it's the actual dialogue to the person she plans to rob of their power. And it is 100% accurate; there is no "spark" she can steal without being hit directly. This level of candour makes sense only if there is an actual point to the ritual, and her subsequent attempt at taunting them is desperation because the ritual does not work, so then, at that point, she has to make do with what she has. Not if the whole thing was a sham to begin with.
I agree it's strange she would warn her about her ability if she planned to have them attack her, but Alice did in fact use her powers on her later without thinking about those consequences. So maybe Agatha hoped she would forget or not show restraint once she angered them enough. The witches in the past all seemed very eager to attack her after being taunted, and seemed to have been working for her for centuries too, so why not now?

Hone made aishite? Akane koi o fukuzatsu kossetsu - S1-E5
Plot hole: Dr. Tofu is able to tell that Ranma was hit by a softball (he says something about the marks like he actually sees them), but Ranma's wound is still covered by the bandage, that he'll remove in the next episode. This is linked to a larger mistake in the following episode. (00:19:55)

Into the Mouth of Evil - S2-E23
Plot hole: While fleeing the guru's disciples through a narrow side street, Jackie gets cut off by the van driven by Dr. Jamba and associates, stun-sprayed in the face, and then loaded into the van. But with three brutish-looking guys being so close to their quarry, the real crooks can take the time for dragging Jackie around to the back door instead of loading him through the side doors?

Plot hole: In Russia, Soldier Boy is shown heading to the airport, He wanted to get to the US and start his revenge against his team. Problem is: he has no documentation and money to take a flight. Even if he stole the money somewhere, still would be impossible to travel without the proper documents.