Maybe it was just a cut in production costs, but near the beginning when Ted Denslow approaches Coop about creating the National Baseketball League, people start falling off the roof... Look in the background when the camera is on Coop, then compare it to the next shot showing continuing action... It's the same exact thing that just happened.
Yea, so what, it doesn't matter if they re-use footage as it is easier then having to film it AGAIN if you can just show it again. I have spotted it a few times in the film, theres nothing wrong with it really, just saving time and even money.
They did it in Saving Private Ryan when the soldiers came out of the ship you see them getting shot on a close up, but when you see the Germans firing there automatics at the soldiers in the ship, its the same footage just using a different camera.
It's been used in loads of films, so this isn't really a real slip up.
There's some more re-used footage at Denslow's will reading. Watch Coop come in with a lady in orange behind him. Later on Yvette and Baxter are talking. Look at the door and you'll see Coop come in again with the same lady behind him. Then the scene cuts to Coop sitting with Jenna again.