When Rachel is singing the first verse of "Don't Stop Believin'," all the background singers are completely out of sync.
During the season's finale, while Sue Sylvester is introduced as a judge, she is said to have won 5 National Cheerleading competitions. However, on the previous one, "Funk", she is shown winning her 6th national title.
No panel of judges would include a faculty member of one of the competing schools.