Continuity mistake: In Season 3, Episode 2 during a conversation with Miguel's wife Sylvia, (Syl), and Rita in a kitchen, Syl says that they don't have any children after trying. In this episode, Syl is trying to help Dexter sell his condo and says that she downsized and focused more on "the kids."
Revealing mistake: When Dexter enters his apartment and finds Zach dead in the chair, you can see Zach's chest moving, showing he's breathing. (00:49:45)
Make Your Own Kind of Music - S8-E9
Continuity mistake: Scene with Deb and Joey having lunch. Their water glasses switch between having ice and lemon wedges, to having no ice and a lemon slice floating at the top. (00:20:15)
Continuity mistake: Quinn brings Deb into the interrogation room and puts his coffee cup down about 6-8 inches from the end of the table. He then moves his chair and begins to talk to Deb without touching the coffee. In the next several shots the cup has moved to the middle of the desk, and the amount of steam rising from the cup keeps increasing as it sits there.
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.
Remember the Monsters? - S8-E12
Plot hole: A couple episodes prior, Deputy Marshal Clayton stated that he shared Hannah's picture everywhere after receiving a tip that she may be in Miami. In the same episode, Hannah was spotted at a hospital and Clayton was called in about it. This should have only increased public awareness concerning her, but at the beginning of this episode, she somehow made it through airport security and all the way to her gate before spotting Elway and hiding from him in the ladies room.
Scar Tissue - S8-E4
Continuity mistake: When Debra is talking to Jacob Elway, a piece of salad appears on her fork and disappears the next second. (00:31:55)
Remember the Monsters? - S8-E12
Revealing mistake: In the flashback scenes when Dexter and Deb are shown holding baby Harrison in the newborn room, you can tell they are just holding a dummy in the wide shots because the baby never moves a muscle.
Continuity mistake: In the shot where Angel gives Dexter a gift from the recently deceased Maria's office, we see Masuka through the window in front of Dexter. Masuka then enters Dexter's office, showing Masuka in two places at once for at least two seconds. (00:30:55)
Suggested correction: That's not Masuka we see in the window. Not only is the person seen through the window wearing a different shirt, he's not bald like Masuka.