Factual error: At Eagle's Nest, Victoria removes a bullet from Frank's arm and drops it in a glass of water. After this point, the blood on the bullet doesn't seem to make the water change color. Even if it's vodka, the liquid should still go partly red. (00:57:50)
Continuity mistake: When Frank meets Sarah in the flesh for the first time, she throws numerous items at him. When she picks up a candle holder and throws the candles at him, a third of one of the candles remains stuck to the holder. After Frank tells Sarah, that people are trying to kill them, Sarah replies "Why would anyone want to kill me?" In this shot, the third of the candle is currently on the right hand side of the candle holder. Then when Sarah says "Why?" after Frank says they've been listening to their conversations, the third of the candle is now on the left side of the candle holder. (00:12:05)
Continuity mistake: After Frank injects the assassin, the syringe injected into his neck is horizontal. However, when one of the assassins shoots a grenade inside, the same assassin that Frank injected now has the syringe in a vertical position. Frank never moved the syringe, nor could anyone else since they were dead. (00:08:00 - 00:09:30)
Continuity mistake: In the Russian Embassy, Frank meets up with Ivan. During this scene, Ivan opens a bottle of vodka. In the shot after Ivan says "As we get older, things seem less important", it is visible that the bottle is filled to the top. He then takes out two shot glasses and fills the two of them up with vodka for both him and Frank. When Igor says "To Igor. The Butcher", we can see that the level of vodka has gone down by a far smaller amount than two shots' worth. (00:45:10)
Audio problem: When the Victory Fund Gala begins, when the woman next to the metal detector gives Victoria her necklace back, Victoria replies "Thank you, ma'am", somehow without pursing her lips on the "ma'am", revealing it's a dubbed line. (01:21:45)
Continuity mistake: Just after Frank knocks out Alexander Dunning, the scene cuts to Sarah and Victoria having a conversation about how she met Frank. At one point during this conversation, Sarah says "Of course now I'm a fugitive and the CIA wants to kill me and I'm hiding in a hole". Right at the end of the shot where Sarah says this line, it can be noticed that her lips are apart. In the immediate following shot her lips are fully closed. (01:03:45)
Chosen answer: Intimidation. The implication is that he's going to be spilling Dunning's blood during the interrogation and doesn't want to get his suit dirty.
Captain Defenestrator