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.
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: 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.
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)
His Last Vow - S3-E4
Plot hole: Sherlock manages to convince Janine to let him into Magnussen's quarters after deceiving her into thinking he is going to propose. Several days later, she is enjoying her "revenge with profits" on Sherlock for his duplicity. Problem: There is no way she could have found out. She was out cold moments after letting Sherlock in, and Sherlock himself was shot by an assailant, which he had misidentified. Only Watson knew Sherlock's true intention, but we know he did not reveal it. The shooter and Magnussen did not know and had no opportunity to tell Janine anyway. (Plus, Magnussen's credibility is too low.) In fact, if I were the director, I wouldn't bother making up a motive for being a "grasping, opportunistic, publicity-hungry, tabloid whore" (film's own quote). Such a person loves "profits", not just "revenge with profits." (00:31:00 - 00:43:00)
Plot hole: When Mr. Ballentine is telling Emily about her assignment, he sets the blue folder down near his side of the desk before he gets up. Then we see Emily pull it across the table and quickly peek in it. When Ballentine turns around, the folder is still close to Emily, which shows that she at least tried to look in it, yet Ballentine says nothing about it no longer being in the spot where he set it down. If Emily thought that it was okay for her to look in the folder, she wouldn't have waited for Ballentine to turn around before she touched it.
The Best Years of Your Death - S1-E3
Plot hole: In the chapel, you can see the heads of those who tried to cross Harriet (the mad matron) preserved in formaldehyde. How did she get hold of so much of it? Wouldn't her husband or the headmaster be suspicious?
Plot hole: When Bryce's body is found, there is a gaping hole in the back of his head, leading to speculation that he was shot. It is later determined that the hole was from blunt force trauma. However, when we actually see his death, he is simply pushed off the pier and ends up drowning. It wouldn't have been caused by his fight with Zach, as he would have been dead long before he could have been pushed into the water. And if the wound was somehow caused by aquatic predation, the forensics experts would know the difference between that and blunt force trauma.
The Man Who Was Never Born - S1-E6
Plot hole: Andro has memorized "every detail" of Cabot Jr.'s life, including his mother's name, Noel. Yet when he travels to the past, meets Noel and learns her name, he still mistakes Cabot Sr. for Cabot Jr., who isn't born yet. Having memorized all those details, he would have known the moment he met her that Noel was Jr.'s mother. Andro's confusion makes no sense. (00:28:00)
Plot hole: Several shots show Barnaby reviewing a newspaper announcing a new death in Strangler's Wood, the Brazilian Woman. No one supposedly knows who she is, as the article states, but the photo of the dead woman is a professional headshot from when she was alive. How could they have obtained her headshot if no one knows who she is?
Suggested correction: She had it with her, as she was a model/actress.
Remember the Monsters? - S8-E12
Plot hole: In order to elude Elway at the airport, Dexter fills a backpack with random items and leaves it unattended under a seat, and then tells a desk clerk that he saw Elway deliberately put the backpack there and walk away, which leads to security detaining Elway and the airport being evacuated. Airports have security cameras everywhere, so security would have reviewed the footage and seen Dexter was the one who placed the bag there. They then would have gone through all security footage since he entered the airport in order to deduce his identity and then located and arrested him.
Casus Belli - S6-E5
Plot hole: Later in the evening, after NYPD takes Quinn into custody, Carrie finds his cell phone, with pictures showing their home had been spied upon from across the street, as well as other evidence of a conspiracy. He had tried to hand her the phone right after the police broke in, but it was knocked from his hand and she discovered it under the smashed door. In the real world, Carrie's home would have been considered a crime scene and the police would have searched it thoroughly, top to bottom, undoubtedly finding the phone themselves, but are shown driving away after the confrontation.
Plot hole: When Beverly is killed the killer shuts off the main power switch which would have turned all the lights off in the house, not just those in the bathroom. (01:31:00)
Plot hole: When Two-Face and his men have broken into the new D.A.'s office to find dirt on Rupert Thorne, one of his men finds a file detailing Thorne's record of Swiss bank accounts, money laundering, blackmail and payoffs that Two-Face tried for years to subpoena when he was D.A. When Thorne finds out that Two-Face has the file, he states that he will be ruined if Two-Face gives the file to the police. If Two-Face tried unsuccessfully for years to subpoena the file, then in all likelihood that means Thorne paid off the right people to prevent the subpoena from happening, so Two-Face giving the file to the police shouldn't be a problem for him. Additionally, if giving the file to the police would be all that it would take to bring Thorne down, then the new D.A. could have already done so. If the new D.A. was also paid off by Thorne, then it wouldn't make sense for Thorne to allow the D.A. to keep the file since they could easily lose the file or even double-cross Thorne. (00:10:45 - 00:14:20)
The Tale of the Mystical Mirror - S5-E3
Plot hole: It makes no sense that Ms. Valenti gives all of her employees a compact mirror and also invites them to her home. Any of them could open their mirror while standing near a painting of Ms. Valenti and they would discover the secret, as Cindy does.
Suggested correction: She isn't concerned about employees seeing her true reflection because she was planning to capture three of them at her home anyway and transform them into dogs for the ritual. Presumably, if she had finished the ritual - and she almost did - she would keep her youthful appearance and no longer look older in mirrors.
Suggested correction: The compact mirror includes a palette of cosmetics. Cindy shows it to Laurel, who says, "She gave one to me, too, like we're ever gonna use it." Presumably, the employees are mostly using the free samples of cosmetics from the shop displays. I myself have owned some compacts that I didn't always want in my purse (if they were too big or awkward in a certain purse).
Explorers on the Moon: Part 2 - S3-E12
Plot hole: In the flashback, Wolf wakes up to find out Jorgen is in his bedroom. The problem is Wolf wakes up before Jorgen even enters the bedroom.
Plot hole: Matlock figures out that The Professor wouldn't have been able to see the security guard from 50 yards without glasses, and that's what tips him off about The Conspiracy: the guard testifying that the man wasn't wearing any. However, when we see the scene happen at the beginning of the episode, the person posing as Prof. Erskine Tate is, in fact, wearing glasses. (00:04:15 - 00:22:15)