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.
Prom Queen - S2-E20
Continuity mistake: When Blaine and Kurt are in Breadstix talking about Prom, the amount of soda in both of their glasses changes between shots.
Prom Queen - S2-E20
Continuity mistake: As Kurt and Dave are talking in front of Kurt's French class, a short girl with a brown ponytail enters the class twice.
Continuity mistake: Near the end of the episode, when Mr Schue is talking to Terri in the school hallway, there are several people walking around in the background and there is even one student running towards the camera. In the next shot - one second later - the hallway is completely empty.
Continuity mistake: While Santana is singing "Back to Black", Jessie is seen obviously scribbling something down. Yet at the end, his notepad is shown with a drawing of a cat upon it. If he was drawing the cat, he would have been drawing smooth lines, not scribbles, as the drawing contains no scribbles at all.
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.
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.
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: Puckerman is on a skateboard and then jumps on to the bench, but the skateboard just disappears.
The Purple Piano Project - S3-E1
Continuity mistake: Blaine has finished singing and the piano is ablaze. Several Club members are seen sitting at the table, then a different view shows only Rachel and Kurt and empty seat spaces where others were sitting.
Continuity mistake: When Rachel and Finn are doing their toast, the amount of cider in the glasses changes between shots.
Continuity mistake: Just as Kurt is pulling up a chair next to Blaine in the Lima Bean scene, Blaine's arm is down by his side. Yet when Kurt hooks their arms together in the next shot, his arm is on the table.
Continuity mistake: The DVD Tina brings Mr. Chang. When she leaves she picks it up from the desk, in the last shot it is back on the desk. (00:17:38)
Continuity mistake: During "Control", Blaine's jacket can be seen repeatedly switching from closed to open. Most noticeably when the chorus shouts "oh yeah" and he's seen high-fiving another member of the group on the right of the screen. This is shown two consecutive times from two slightly different angles. The First Time his jacket is open, the second time it got buttoned up. (00:28:25)
Extraordinary Merry Christmas - S3-E9
Continuity mistake: When Kurt and Blaine are singing "Let It Snow", during their last long note, Kurt places his hand on Blaine's back. In the next shot, it's back by his side.
Continuity mistake: When singing in the choir room with Finn, Rachel's necklace changes from inside her dress to outside several times.
Continuity mistake: When the Warblers fill the cup up with rock ice, you can see the cup is empty, yet in the next shot it's full of Slushie and no rock ice is in there when it's thrown in Blaine's face.
Answer: According to IMDb.com, Ian Brennan, one of the "Glee" writers and producers, is listed as the uncredited narrator voice.
Michael Albert