When Moze is talking to Ned and Cookie by the lockers in the beginning of the reading episode, you can see that to the left of the screen Ned's locker is open. But when they go back to Ned and Cookie, Ned is just opening his locker.
After pushing Principal Pal and sending him away on skates, Gordy, Moze, Ned, and Cookie are standing in front of Pal's office. Gordy realizes his mistake and acknowledges they are on the 2nd floor. They then split up and end up on the first floor. However, after Pal comes down the stairs, you can see his office in the back as he skates toward the group.