Factual error: In season two the show makes Dalton look like it's in a suburb of Lima. Dalton Academy is suppose to be located in Westerville, OH, which is two hours southeast of Lima. Kurt & Blaine would not be able to go to the "Lima Bean" coffee shop every day if this was the case.
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.
Trivia: At various times throughout the show you may notice Chris Colfer has a large red scar on the left side of his neck running from about half way on the side to the back of his visible lower hairline. He had surgery when he was eight to remove an infected lymph gland. It is most noticeable when singing "I Wanna Hold Your Hand" in "Grilled Cheesus" (00:28:05-00:28:15)and numerous times "Candles" on "Original Songs" (00:28:10, 00:28:20, 00:28:55 & 00:29:05-Most Noticeable).