Our Father - S3-E1
Revealing mistake: During the crime scene investigation where Dexter, Masuka, Debra, and Angel arrive, a production mistake is visible. The victim, who is supposed to be dead, can be seen breathing - the back moves slightly while the camera is still on the body. (00:52:45)
Revealing mistake: The actor portraying a dead body noticeably moves her left leg while being turned over by Angel, Dexter and Masuko. (00:06:33)
Revealing mistake: In the scene where Rudy's body is found by the police, you can see Rudy breathing and his pulse in his neck. (00:51:05)
Revealing mistake: When Dexter is retrieving a blood sample after cutting Benny Gomez's cheek, there is no blood in the dropper and he puts no blood on the actual slide. (00:49:50)
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)
Dirty Harry - S4-E5
Revealing mistake: After the intro at the start, it cuts to Dexter passing the fire engine, and the next long shot with a firefighter lifting the yellow tarp is a flipped shot; note the backwards licence plate, sign, etc.
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.
Revealing mistake: The dead body appears to be moving its eyes. (00:10:05)
Revealing mistake: When Dexter stomps on Barry's kidney, you can see his foot doesn't even make contact with Barry's body.
Revealing mistake: After Doakes remarks that the dead body of Eva is a message, you can see the actress' neck throbbing around where the trail of blood is. (00:06:49)
Revealing mistake: When Deb is texting "Looks like it" to Anton, the buttons she presses on the keypad do not correlate with the message itself and the phone doesn't show any auto-correct feature being utilized, indicating that the text message was added in post production.
Revealing mistake: When Valerie's dead body is on the table after being brought up from the ocen by the ice truck killer her nipples are hard. If she was dead her nipples would not have any reaction to the cold.
Revealing mistake: When Rita confronts Dexter about his accident being more than minor Rita turns the buggy with the baby in around to leave and it is clear the baby is fake. (00:38:20)
Revealing mistake: When Dexter is fighting Liddy, in the van after kidnapping Dexter, the knife is a rubber fake knife. (00:38:15)
Sunshine and Frosty Swirl - S7-E2
Revealing mistake: After Isaak Sirko killed Tony Rush by sticking a screwdriver in his eye, Rush almost instantly drops dead on the floor. When Sirko's assistant, Jurg, wipes the screw driver for finger prints, you can still see a pulse at the base of Tony's throat. (00:54:05)
Answer: No, Harry is not the real father. While he did have an affair with Dexter's biological mother (Laura Moser), this was when she was his C.I. Dexter was already born at that point.