Continuity mistake: Emily Sloane's left ring finger was shipped to Arvin Sloane in one episode in Season 2, when they are reunited in the Philippines, the left ring finger is bandaged and missing. Later, in the episode when she is shot, when she tells Arvin the CIA is listening, the left ring finger is there.
Continuity mistake: When Flash plays tag with Faust ("Now you see me, now you don't"), there is a brief shot in which he rushes at Faust - but not inside Hyppolita's palace, but in some high-tech laboratory. Obviously a shot from some earlier series, since the coloring and style are different from the Justice League's.
The Catwalk - S2-E12
Continuity mistake: T'Pol says she has never been camping, but she went in "Strange New World."
Continuity mistake: In the bootcamp scene where Captain Sobel is yelling at Private Christenson for drinking from his canteen, you see a machine gun resting on Christenson's right shoulder. When the camera angle changes to behind Christenson, the machine gun has suddenly moved onto his other shoulder. This happens quite a few times in this particular scene.
Continuity mistake: When Aetius is about to leave Rome, he tells Valentinian he's going to Ravenna to take command of the 3rd Legion. The banners of this legion, however, have "LEG XX" on them, which means this is actually the 20th Legion.
Episode XXVII - Chicken Jack - S3-E1
Continuity mistake: Jack's father the emperor is a young man when he defeats Aku. At the conclusion of the movie, he greets his pregnant young wife. At the start of "The Beginning" movie, Jack is a very young boy, both his parents are well past middle age-and Jack has no sisters or brothers to explain the gap.
Crime of the New Century - S1-E9
Continuity mistake: In the fight scene at the start of the episode, Jesse knocks one of the GS agents into the water - in subsequent shots he has disappeared.