In Stopwatch, when Vaughn closely examined the chi-ball that Josie had left, it had markings on it. But the floating one didn't, and the two balls came together. Why would one of the chi-balls in the box have markings, and the other one not? Shouldn't they both be the same?
Lucas says that Josie and Vaughn were more friendly ever since Brainwaves. But it looked like it was with Lucas that she was being more friendly with like in Chemistry and Technology, not Vaughn.
Even though Professor Z says that pop quizzes are not his style, he didn't hesitate from giving one in the episode "Thursday."
Josie's shirt that says Original, is a Puma shirt, but the symbol of a puma underneath original is covered up by a white piece of cloth.
This is the second episode that Marshall [and everyone else] takes the midterm.
When Vaughn reads about Powernut for the first time, there is nothing on the vending machine saying what he is reading.
When Corrine and Marshall kiss, Marshall bites his lip when the camera is up close then again real fast when the camera is farther back.
Josie is wearing pink in the mirror, and Corrine said that she will not touch the color pink. In the first episode, Wormhole, when Josie moves to Blake Holsey, she is wearing a pink jacket.
Corrine claims she can't sing outside of the shower. This is incorrect because we have heard an excellent voice from her in the episode "Storm".
Lucas said that he found a whole box of the Pearadyne computer chips in his and Marshall's room, why did they all go into the basement to look at a box of the chips?
When Principal Durst goes to return Marshall's cell phone and finds both phones missing, when did she confiscate them? She gave Tyler's phone to Professor Z and Marshall kept his phone, then they reversed the encryption code on Marshall. The giving of both phones to Principal Durst was not seen and doesn't seem to fit correctly with timing. If it occurred when Marshall was telling Principal Durst the truth, Victor would have had no chance to take the phones.
Marshall shrugs when asked what site he got the computer code from but was able to correctly tell them the internet path later when they were in his room.
When the liquid is spilling from Prof. Z's cup, it's almost transparent implying that the liquid was coffee but when he's mopping it off the floor it's brown tea.
First appearance of Magnet 360.
In Chemistry when Marshall is Neon, there's a bit when he's sitting or standing right next to a window - you can very clearly see reflected in the glass a very normal, non red, non glowing Marshall.
Although the Helium atomic model seemingly picks up balls from the nearby box, nothing in the box moves, the balls appear to have materialized out of air.
The Chlorine atomic model has less than 17 electrons while the Sodium atomic model only has 9 atomic atoms, the correct number of electrons in Chlorine is 17 and the number in Sodium is 11.
Vaughn has dislexia.
Before Lucas and Vaughn switch for the first time, the patch on Lucas' forehead has the wire on the side, but after they switch the wire is going straight down his face. (Contributor: karategrl)
When Durst gives "the lucster" detention she says it is for this afternoon, but then when Lucas was about to confront Victor and Josie pulls him aside she reminds him of being put in detention for that and he said that he has to be out of detention b/c of the fight at 3pm......so why didn't he go? Wouldn't he be in more trouble?