Continuity mistake: In the "Singing In the Rain" dance, the second time the three guys are on their knees, they splash water with their hands. The third time they splash, the water drops are moving toward the stage instead of away. And the rain in the background is falling up.
What the World Needs Now - S6-E6
Continuity mistake: When Rachel is singing the final long note of "Promises, Promises," she slowly raises her arms to above shoulder level. Then, a shot from behind shows her arms well below shoulder level, then a return to a front shot shows her arms slightly above shoulder level again.
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: When Rachel and Ms. Corcoron sing "Poker Face", near the end they switch places between shots.
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.
Answer: According to IMDb.com, Ian Brennan, one of the "Glee" writers and producers, is listed as the uncredited narrator voice.
Michael Albert