From 0:04:41 to 0:06:30

So, super important magic mirror is left completely unguarded inside a room, and it is not locked... also, that guard in the hallway is making a terrible job.

Tripping over the dragon's tail after she passed all the guards and all that like some ninja... really? Also, if she could levitate the crown, why didn't she do it from the door? Did she have to walk into the room?

Also... How did Sunset know that the Element of Harmony would be right there? In that exact night when the portal could open? True, she could have just assumed that the mirror would be still in Canterlot castle, where it was when she first entered it all those years ago, but even then, how does she know her way around the Crystal Empire castle, a place she could never have seen before, and find Twilight's room, and know that the Element of Harmony was there? Her plan has more loose ends than the one used by the bad guy of 007:Skyfall...

You know, for a Pony that has spent the last decade in a world where she's a human with no magic, Sunset is really good at walking in all fours again and using magic.

Isn't Rainbow Dash one of the fastest ponies in Equestria? Why shouldn't she be able to get Sunset in 10 seconds flat?

Metal crowns don't bounce that way... also what are the chances it would fall right in the mirror?