Really, that’s kind of fitting for Caitlin, seeing as how her powers were revealed last week, and she briefly abandoned the power-controlling cuffs that Cisco designed to help Barry.
In the movie, the song was sung by the character Elsa, who had the power to control ice and snow.
And, choosing “Let It Go” as the Easter Egg was pretty perfect, too.
The song from the 2013 movie became an instant hit upon Frozen’s release.