Factual error: They repeatedly say how equipment will freeze in moments, but they leave their faces exposed and coats open, hoods off at times. In such cold temps, the skin would freeze in minutes.
Extinction - S4-E1
Character mistake: Happy determines that the nitrogen hydroxide ate through the drum because it was "steel alloy," in contrast with Walter's requirement that it be "pure steel." These terms are inaccurate, and would not be used by technical experts like Happy and Walter. Every steel is an alloy, combining at a minimum iron and carbon; steel with other alloying agents is called "alloy steel," not "steel alloy." Because steel doesn't refer to one specific substance, "pure steel" could never be used to specify a material for a given application.
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)
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)
Factual error: Walter gives the volume of additional air/oxygen from the tank as "298 cubic liters", it is either cubic ft, cubic meters or simply liters, not cubic liters. (00:32:35)
Revealing mistake: When Ralph is talking to the Special Forces Unit, the spectrogram at the bottom of the screen does not match the voices from any characters or the gunshots.
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)
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)
Other mistake: When Happy goes to see if the backhoe will work to finish freezing the water she says the hoses are damaged. The hoses she indicates as damaged are the ac lines and hydraulic lines that hydraulic oil flows through - she does not even look at the water hoses. (00:18:40)
Plot hole: They need at least 12 magnets to make it work, Paige collected 11. (00:21:00 - 00:22:00)
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)
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)
Answer: A propeller sucks in from one side and pushes away from the other side.