Other mistake: An extra is walking in the background with a measurement wheel while Debra is talking with Lundy outside of the warehouse. The character is hovering the wheel over the ground and not actually using it for its intended purpose. (00:17:10)
Character mistake: In this episode, as well as 1-2 others, Dexter holds his slide phone upside down (only in the edits/cuts where he wasn't shown answering the phone). When the phone is slid open, the front cover goes above/higher than the backside of the phone. And a few instances I've seen, the side closest to his face 'lower' than the outside/backside of the slide phone, strongly suggesting the phone was held upside down.
Continuity mistake: Deb moves in with Dexter to his apartment in a 2nd bedroom during season 2 following the ice killer's kidnapping and attempt on her life. But in Season 5 when they try to share this apartment again, it's only 1 bedroom now?
Do You Take Dexter Morgan? - S3-E12
Other mistake: Debra is checking her email for the traffic cam photo of George King. The sender is labeled "Miami Metro Robbery Div." and the subject is "Photo of George King." However, after opening the email, the send is then a malformed email address of Det.Robertson.Robbery|MiamiMetroPolice.web with a recipient address of Debra.Morgan.Homicide|MiamiMetroPolice.wed (wed, not web), with a subject of "B. O. L. O. Match - George King." (00:26:38)
Other mistake: Lumen agrees to meet her former fiancé Owen at noon. When they meet up, the sun setting in the background indicates that it's evening. (00:16:12 - 00:23:39)
Other mistake: There's no way Arthur could have known Scott was 10 years old. In fact, it's highly likely he would not have known any of the boys he killed were 10 years old.
The Getaway - S4-E12
Other mistake: The tub Rita was found in was full of water, to the rim. Volume displacement dictates that when Arthur got out of the tub the water level would have dropped to well below the tub's rim.
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.
Dirty Harry - S4-E5
Visible crew/equipment: After the ambulance taking Deb to the hospital drives away, a crew member ducks down in front of a parked car in the background. (04:36:00)
Continuity mistake: When Dexter is packing kill tools for the road he "packs light" and chooses a knife and hammer. However once he's at the hotel room setting up the kill room he unrolls his entire set of tools like he does at all the other murder room scenes.
Revealing mistake: When Dexter is fighting Liddy, in the van after kidnapping Dexter, the knife is a rubber fake knife. (00:38:15)
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.