I found this out the hard way on Saturday, and I bet
Equusmaximus has/will, too. The whole first pressing of Equestria Girls - Rainbow Rocks has a significant error that makes the movie very, very confusing.
Returning the DVD set to the store did not work, they're ALL affected - and Walmart has strange new policies if you exchange it without the receipt, as I had to do on Monday because it had blown away or something on Saturday while I was running around shopping. For some reason they open up the *new* DVD set to check it, and don't give you any paperwork at all to prove it was in exchange for a returned product (and btw, it was the Walmart exclusive set with the CD, so there was pretty much no way they could say it came from another store).
The good news is that Shout! Factory will replace the disc totally for free. They do ask for an image of the receipt, but I (begged) explained the sitch to them and just got notice that mine has shipped! :D
At least the soundtrack is on iTunes, and sounds pretty great (tho the bonus track is strange and a bit offputting)! I re-ordered them in movie order, then burned them to CD. Warming: Trixie's song is an ear worm! :D
--Zhora