As Lotor is watching the Lions on the monitor, the color of his helmet changes. When they cut to the shot from behind him, the helmet is all white, but when they show him from the front, it is the usual black with silver blades sticking out.
When talking to King Alfor, Allura is in her Voltron Force uniform. During the conversation, they cut to a stock footage shot of her in her regular clothes. With the next shot, she's back in uniform again.
While searching for Allura, they cut to a split screen. On one side of the screen, Pidge says, "There's no sign of the Princess anywhere." However, on the other side of the screen, you can clearly see the Blue Lion flying with the rest of the team.