Orpheus in the Undergrowth - S2-E2
Plot hole: When Jeremy stopped to drink his water, which turned out to be vodka and which killed him via a heart attack, why did he hide himself away, surrounded by plants and only found by his mobile ringing? And why would he put the lid back on the bottle in the throes of a heart attack?
High Octane - S5-E7
Plot hole: When Dex is doing the jack in the box ,he is hanging out the sun roof driving with his feet, using the cruise control. When he is decapitated, the body falls and the car spins out and stops. The car's cruise control was still on. The car should have kept going until the brake was pressed. Even if the body hit the brake on the way down, it would have coasted to a stop and not spun out and screeched to a stop.
How I'm Spending My Summer Vacation - S2-E17
Plot hole: When Kevin is upset about Paul leaving for summer and is just lounging around the house, he asks why they can't go on vacation. His mom says "Maybe next Summer." In the very next episode, which takes place in the same Summer, they are going on a "traditional" Summer vacation.
Plot hole: When Emily is dialing a number for Manny Martelli, to make arrangements for the funeral, she only dials two digits. She just got the number from someone else, so there's no way it was speed-dial.
Episode #1.5 - S1-E5
Plot hole: Leon Hamilton is the most hated man in Sainte Marie, with over 900 people on the island conned by him. Yet exactly one person in the whole island knows how he looks like, every newspaper and website never ever published a picture of him even during the very public trial when they were trying to get their thousands of dollars back nor publish an archive picture after his death.
Plot hole: The pictures James took were developed from his camera into photos even though he was arrested while taking those. How did they get developed? James' father didn't approve and his mother said she had found that stack of photos after the police searched his room. (00:26:30 - 00:30:00)
This One Time at Space Camp... - S4-E18
Plot hole: When Dr. Hughes is racing to save Allison when he thinks he is Carter from the events that happened in "I'll Be Seeing You" Henry says he is racing for a cliff, and that the cabin was just a hologram. But in the episode the Cliff was the hologram disguising the cabin. Henry even commented in that episode that he did not remember a cliff being there.
Plot hole: How do they travel all over so quickly? Why does it take the same amount of time to travel from one continent as it does city to city? Someone in Paris talks to another in Zambia and bam, they're together all of a sudden.
Plot hole: The car was tracked down by finding the original car key on Jimmy's body. If he had stolen the car from the original owner, how did he come to have the original car key?
The Inspired - S9-E2
Plot hole: At the beginning of the episode, PD let the suspect go (twin 1) because they accidentally arrested him for the crimes that his twin brother (twin 2) committed. Hotchner still wants to question twin 1, but a lawyer threatens Hotchner to not go near the wrongfully accused twin 1. However, in the previous episode, FBI and cops pursued twin 1 and twin 1 didn't pull over. It would be legal for twin 1 to be detained on a reckless driving or eluding the police charge.
Here There Be Monsters - S1-E10
Plot hole: The female police officer has a theory that Johnny was the Strangler in the case the papers claimed he helped solve but this hardly makes sense. If she was researching him as was seen in the episode, surely it would have said something about Johnny being in a coma during the bulk of the murders since the story was about Johnny.
Plot hole: Towards the end of the episode, Mr. Alderman ties up Cherry Peck and forces Matt to cut off Cherry's male genetalia. Matt does so, and Cherry screams in pain. Later on that night (probably at least an hour later in what would be "real time"), Mr. Alderman and Matt drive to a secluded area and Mr. Alderman forces Matt to bury Cherry alive. Matt refuses, and Cherry eventually steps out of the grave and strikes Mr. Alderman with a shovel before shooting him. Cherry has the same clothes on, but is in no sign of pain, or is even bloodied from the earlier trauma. It is safe to assume that neither Matt nor especially Mr. Alderman would have driven Cherry to any hospital, nor would any hospital even have let her out in an hour or two's time after an injury like that.
Plot hole: In episode 1-7: "Unraveling," Christina and Jesse get on a bus to New Haven, first thing in the morning. Christina left the Kramers's house before breakfast. Then, they ride on the bus all day until getting trapped in a terrible storm in the dark of night. But New Haven, CT, is less than a seven hour bus ride from the Jersey shore, so anything that happened to them on the way there should have been in full daylight.
Another Mother - September 30, 1981 - S2-E13
Plot hole: Sam wallops both kidnappers and rescues the son. They then leave the two child molesters unconscious beside their van. No one calls the police or has them arrested, so they're free to kidnap another kid. Sam doesn't leap until after an epilogue in which the loose ends are supposed to be resolved - but this question is left unanswered. It's not excused by a "just because we didn't see it happen doesn't mean it didn't" defense. The viewers shouldn't be left with a dangling plot hole, and one line could have cured this one.
Plot hole: Xena is posing as a guard outside of Caesar's office. She knocks out the 2nd guard and throws him on the ground. Moments later, about 10 guards walk by, but no one notices the passed-out guard on the floor. (00:14:40)
Plot hole: At the start, they state that they have 96 criminals to go. They bring up the photos of all 96 wanted felons. They then learn that Machado has been pushed to the top of the list and they bring up his file. You can see his mug shot on the screen, among the list of 96, as they zoom into his file. If he is in jail and has not yet escaped, how can he be in the list of 96?
Plot hole: In the first season, Lucy Ewing had an affair with Ray, the farm hand at South Fork. Several years later, it was revealed that Ray was actually Jock Ewing's illegitimate son, making him Lucy's uncle. However, the subject of their affair was never raised, even though they surely would have been at least somewhat traumatized upon learning of the accidental incest.
Hit and Run at Danny's - S2-E6
Plot hole: There are three mistakes in one scene when Quincy talks to the driver of the hit and run car and he finds seatbelt bruises on the right side of the throat under an arm sling. First mistake: The bruises will hurt a lot and won't heal if they are under a sling. Second mistake: At the beginning, when the driver struggles with the kidnapped lady while driving he has no seat belt on which touches his throat. Third mistake: When you put a seat belt on sitting in the driver seat the belt will surely touch the left sight of your throat - not the right. (00:39:05)