Other mistake: The Doctor, coming up from the basement of his house, is locking both deadbolt locks using a key held in his right hand. He logically would use the same hand to put the key in his upper left pocket. Richard who is watching through binoculars uses a walkie talkie to inform both Ezra and Jules that the Doctor has put the keys in his upper left pocket. However, the next scene shows the Doctor with keys now in his left hand placing the keys in his upper right pocket. This doesn't match what Richard says he observed. (00:24:42)
Continuity mistake: During the shoot-out near the end, the bullet holes in the pillars Frank and Kyle hide behind change and also disappear at various times. In one shot we see 2 holes when Kyle steps out to shoot, then when he ducks back when fired upon, the 2 holes are gone.
Continuity mistake: During the fight with Zhou Cheng, Cheng does a forward flip and kicks Danny, making him stumble backwards. In the shot of Cheng lying on the ground, Danny is holding his stomach. In the shot immediately afterwards, he's holding his chest.
Continuity mistake: Spoiler! At the end of the episode, after Elektra decapitates Alexandra, the blood pattern on her changes changes when she turns around and asks "any questions?" Most noticeably more blood on her forehead and two streaks down her chin that suddenly appear. (00:49:10)
Audio problem: Right after Carol finishes studying by singing a rap to Katie, Katie congratulates her and Carol hurries out. They exchange several lines of dialogue, but it all appears to be dubbed. During most of the dialogue, each character's mouth is not shown when they speak. However, the cadence of Katie's moving jaw can still be seen from behind, and appears to last longer than the audible speech. Additionally, Katie and Carol can each be heard to speak when it can be glimpsed that their mouths are not moving.