Revealing mistake: In scene where Liz is telling captive ex-husband, Tom, that she will let him go after he helps her get Berlin, Tom gets up and you can see the chain on his leg is only held to the floor with a chain link that just screws closed.
Revealing mistake: When Elizabeth Keen removes the tape from Amalia's mouth after rescuing her, she briefly reveals the sticky side of the tape to the audience, showing another large swatch of tape attached to what should be the sticky side. This was done to prevent the actor's skin and provide easier removal.
The Decembrist (No. 12) - S2-E8
Revealing mistake: When turning the guy with C4 around his neck, the 4 person safe box window shakes briefly. If this was a bomb proof safe box, the glass would be at least 1.5"+ in thickness and would not shake simply from some walking. That box would be shrapnel to a C4 bomb inside. (00:26:30)
Answer: The man Red killed, Sam Scott, was Lizzie's adoptive father, not her biological one. However, at that time Lizzie (and thus the audience), was led to believe her real father abandoned her and her mother, so expect more secrets to be revealed how her real father actually died (or if he's even actually dead).
Bishop73