The girls arrive via RV at the Star Swirl music festival, with Sunset and Pinkie being especially excited to see the reunion performance of Post Crush. After a night of rest, they start day one of the festival, but just about every little thing that can go wrong does go wrong, mostly due to Pinkie getting so easily distracted by other things and ultimately causing them to get banned from the festival grounds before they can even watch Post Crush, and Sunset (after sitting alone on a hilltop and mysteriously swept in some wave of energy) goes to bed frustrated at Pinkie and disappointed.
But when Sunset wakes up, it's day one of the festival again. After mentioning her feeling of deja vu, Twilight tags along with her and Pinkie, and upon seeing Sunset easily predict so much of the day's events, Twilight concludes that Sunset has somehow ended up in a time loop. Despite Sunset's efforts, the day ends the same with her and Pinkie getting kicked out before they could watch Post Crush. Sunset wakes up on day one for the third time, and this time decides to not even bother following Pinkie and focus only on being able to watch Post Crush. Sunset is successful, but upon returning to the RV discovers Pinkie has gone nuts from feeling completely rejected, and the rest of her friends are angry at Sunset for it.
Sunset repeats day one of the festival countless more times to the point where she's able to accurately predict every single minor event that happens. Eventually, she gets the idea to simply "run away from your problems" and decides that night to drive the RV away from the festival. Unfortunately, the RV gets badly damaged in the attempt, and Sunset awakens on day one again. This time, she finally realizes that she should send a message to Princess Twilight in Equestria, and receives a reply detailing a magical artifact called the time twirler that could cause such a time loop.
After Sunset shares this information with her friends, they're shocked to discover the Dazzlings are performing at the festival, and are quick to assume they must be behind the time loop. Pinkie's attempt to get past security fails, but it does provide Sunset with information she uses the next time around to bribe him with a kitten to be allowed through. Sunset searches the Dazzlings' van and ends up confronting them, but discovers they had nothing to do with the time loop. Sunset is disappointed at being unable to find the time twirler, but after some encouragement from Pinkie, she decides to spend the next time around doing what she had always intended from the start, and that was to spend the day having fun with Pinkie.
This time, thanks to Sunset's extensive experience from all the previous loops, practically every little thing that went wrong the first time around now ends up going right, such as winning a tandem bike, happily joining Pinkie on everything she enjoyed, and even calmly ordering churros (rather than Pinkie tackling the cart which got them kicked out). That last one even gives them an opportunity (via a disgruntled employee) to deliver churros to Post Crush themselves. However, when they let slip they were expecting a different guy to make the delivery, Sunset gets suspicious, and just when they try to leave, she tricks them with a respectful handshake to allow her to read their minds, allowing her to discover they are the ones who found the time twirler and have been using it in an effort to eventually achieve a perfectly flawless performance.
Post Crush refuses to stop their efforts, and while Sunset believes the effects of the time loop means she can keep trying to stop them, one of them demonstrates that she can always quickly sketch Sunset's and Pinkie's faces and show them to security at the start of the day to ensure they'll never get another chance, and they promptly order security to kick them out. Knowing they now really do have only one chance to stop the time loops, Sunset and Pinkie make an attempt to break back in, but the security guard simply lets them back in after the inspiring words Sunset gave him earlier. Sunset and Pinkie catch up to Post Crush backstage just moments before they're due to perform, and in the ensuing struggle, all four end up on stage and Sunset destroys the time twirler. Post Crush is devastated they'll never get the perfect performance, but Sunset points out that perfection never mattered and what was really important was simply performing together, as indicated by the still cheering crowd. With that encouragement, Post Crush proceeds with their performance and even allow Sunset and Pinkie to join their show. And of course, after going through the same day for three weeks, Sunset is thrilled to wake up on day two of the festival.
First of all, yes, this special obviously follows the same theme of the movie Groundhog Day, but the concept of time loops is something I often find quite fascinating, so I ended up enjoying this special quite a lot. It was also a nice surprise to see the Dazzlings return, albeit their voices sound a little off, though I suppose that could be excused considering what happened to them when we last saw them way back at the end of Rainbow Rocks. (Also of note, Adagio grumbling about "pathetic humans" at one point might be the very first time the word "human" was ever used in the entire Equestria Girls series.) Not much else I can think of saying here, but I definitely enjoyed this special. (Sadly, with production of Equestria Girls recently ended, it was just confirmed today that this really is the final major installment of the series, despite plans for a more definitive finale. All there is left to see now are the rest of the Season 2 shorts that are coming up.)