Continuity mistake: Walter is talking to the Air Traffic Controller on his computer. He tells the controller to look at his 10:00 to see the camera through which Walter is looking at him. The controller turns backward to look at his 4:00. (00:13:50)
Single Point of Failure - S1-E2
Character mistake: In the letter informing him of his sister's condition it says "Nor have I scene" instead of "seen". I would not expect a medical professional to make that sort of error. (00:02:20)
Single Point of Failure - S1-E2
Revealing mistake: Walter accesses code on the sick girl's laptop to trace the source of the virus - aside from the fact that the code comes straight up a fraction of a second after his hands even touch the keyboard, the code displayed in the black window is for a set of traffic lights, with lines like "Walk/Dont_Walk" and "Green_Arrow/Yellow_Slow." (00:08:10)
True Colors - S1-E6
Continuity mistake: Walter and Paige begin dancing and there is a lady dancing in a green dress behind them. In the next frame, that same couple is dancing across the room and then a second later next to Walter and Paige again. Walter's left hand holding Paige's in a dancing position also changes from open to closed. (00:26:05)
True Colors - S1-E6
Continuity mistake: When the wine falls on Toby his shirt is soaked and turns pink. The camera slam cuts to Happy, then back to Toby, whose sleeves are now white with red splotches instead of pink. (00:29:45)
Factual error: One of the characters is playing an Octave Cat. He plays chords, along with a bass line. This is impossible: The Octave Cat is a duo-phonic instrument and can only play two notes simultaneously. (00:35:45 - 00:36:40)
Continuity mistake: The tail number of the plane Walter is in changes. (00:30:00 - 00:31:00)
Answer: A propeller sucks in from one side and pushes away from the other side.