Character mistake: As Reddington sets up the blood transfer between himself and Ressler he inserts the intravenous line in Ressler's arm first and then in his own arm. This way the remaining air inside the line gets into the recipient's body and could very well kill him. Judging the expert way he handles the set up he should know to first insert the IV in his own arm, let the line fill with blood and then insert the IV in Ressler's arm.
Suggested correction: That amount of air would probably not cause any problem. It actually takes quite a lot of air to cause any issue.
Character mistake: Lance and May walk into a bar in Massachusetts. As they enter, the camera pans and shows a large banner on the front window. The banner is advertising "game day" food and drinks. In very large letters the banner shows Boston Red Socks. The actual correct spelling is Boston Red Sox. (00:05:45)
Character mistake: Troy calls for the "Twistornado" but his card reads "Windrive"; the cards have always read exactly what the rangers called for.
Character mistake: The language peculiarity of the series refers to any wheeled vehicle as a "roller." The character "General Tak" accidentally breaks the language rules near the end of the episode and uses the word "car."
Character mistake: Bruce and Alfred play a short game of chess, after which Alfred remarks, "I don't know why we bother playing this game - you never lose." The problem is, Alfred moved into a position wherein Bruce could take his king; this is called "moving into check" and is not allowed in chess.