Continuity mistake: During Season 2, Episode 9 (Special Education), just as Blaine is singing "Hey soul sister, I don't wanna miss." for the last time, he is several feet in front of the other Warblers. But during the next shot, as he is singing ".a single thing you do.", he's right in front of them. So he jumped back several feet between two shots.
Continuity mistake: In "Wheels," when Artie is singing 'Dancing By Myself' and doing tricks in his wheelchair, the wheels on the back of the chair that prevent him from falling backwards disappear and reappear, depending on whether or not he is performing a trick.
Continuity mistake: During "Theatricality", when the boys are singing "Beth", just as Puck sings "Me and the boys are Playin'" for The First Time, Finn is visible sitting behind Quinn. Yet Finn went to sit down and sing with Puck and is obviously sitting with the boys in the next wide shot.
Continuity mistake: In "Hell-O", as Santana and Brittney are talking about the "hottest guys in the school", Santana's glass is almost empty. Yet two shots later, when she takes a drink, her glass is full. Also, when she says "Would you mind waiting in the car?" her glass is full and you can obviously see a slice of lemon in it. Yet in the next shot, when she says "And leave your credit card", her glass is only about 1/3 full and the lemon slice is gone.
Continuity mistake: Kurt informs Blaine that he flew in an airplane for The First Time. This however is incorrect, as Kurt flew to Albuquerque NM for the 2010 Cheerios Championships. In the season 1 episode Sectionals it is mentioned the Cheerios Nationals are in Albuquerque and in the season 1 episode Funk The Cheerios return from Albuquerque the same day. 1500 miles in less than a day means they flew.
The Rocky Horror Glee Show - S2-E5
Continuity mistake: When the kids are practising the 'Dammit Janet' song, Finn draws a heart on the whiteboard in the back of the choir room. The shape of the heart changes with almost every shot it is in.
The Sue Sylvester Shuffle - S2-E11
Continuity mistake: When the Warblers are singing "Bills, Bills, Bills", one of them throws the sheets of music up in the air as he spins. For the remainder of the song, the sheets are on the floor during some shots, but have disappeared in others.
Continuity mistake: In "The Power of Madonna", as the girls are performing Express Yourself, near the end of the song the coats that Tina, Santana and Brittney have dropped disappear and reappear several times.
Continuity mistake: Near the end when Brittany is talking to Santana outside their lockers, Brittany's fringe keeps changing between shots from across her forehead to down the side of her ear every time the camera switches from facing her to facing Santana.
Sectionals - S1-E13
Continuity mistake: In episode 13 "Sectionals" when Will confronts Sue in the corridor about leaking the set-list to the rival teams, Sue is wearing a bag over her shoulder. However, in the shots from behind the bag is nowhere to be seen. (00:16:05)
Continuity mistake: During the musical number "Somewhere Only We Know", you can see Brittany step down from the stairs in the background as The Warblers circle around Kurt and pat him on the shoulder. The next shot shows her stepping down again.
Continuity mistake: When Rachel and Finn are doing their toast, the amount of cider in the glasses changes between shots.
Continuity mistake: During "Don't Stop Believing" at the line "He took the midnight train going anywhere," Rachel extends her hand with her palm facing the floor. In the next shot, it instantly changes to her palm facing the seats of the auditorium. (Timecode listed for the director's cut of the episode.) (00:44:00)
Continuity mistake: During "Never Been Kissed", just after Sue activates the confetti cannons and is talking to Will, the amount of confetti on Will's shoulders changes between shots.
Continuity mistake: When Mercedes is singing "Bust Your Windows", the blue rags on Kurt's car behind her change position several times. Also, Kurt is at first looking up at the hole in his windshield, then has his head down on the hood, and then is looking up at the hole again, over a series of 3 or 4 shots.
Continuity mistake: At the end of the episode when Kurt and Blaine are sat in the Lima Bean, the position of Blaine's hand where it props up his face changes. Whenever we see Blaine from the front, his fingers are curved slightly, but when we see Kurt (and the back of Blaine's head), his fingers are held straight so they do not interfere with the shot.
Continuity mistake: During season 2 "Never Been Kissed", just as the Warblers begin to sing "Teenage Dream", a boy with a briefcase walks in front of Kurt, heading towards the left. Two shots later, the same boy with the breifcase walks left in front of him again.
Continuity mistake: In "The Power of Madonna", during the Cheerios stilts routine, as the people on stilts lift one leg one after the other, they are in a V shape, and there are both girls and boys on stilts. Yet in the very next shot, as the people on stilts swing the other Cheerios around, there are only 3 Cheerios, all guys, on stilts, and they are in a straight line.
Laryngitis - S1-E18
Continuity mistake: During "Laryngitis", Puck pulls Mercedes up to come sing "Lady is a Tramp" with him. Yet in the very next shot, just as she starts singing, she stands up again. So she stood up twice.
Answer: The show is purposefully stylized and over the top. It is not designed to be an accurate, realistic representation of American high school. The idea that the glee club is so unpopular other students can literally throw garbage at them with impunity is an over-exaggeration of how glee club is considered "un-cool" compared to things like football. However, there is a second way of looking at it. The audience is simply never shown anyone getting into any trouble for throwing slushies. Just because we don't see it doesn't mean it never happened.
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