Shadowmancer said:All the song segments have never been meant to be viewed literally, but more as reality + dreamscape, ala lighting where there should be none, background music without any source, costume changes, etc. Some are more real than others, but most, if not all have had elements of fantasy mixed in.
This sequence I took to be how the two girls heard their favourite song in their own heads as they were singing out loud.
This. I kind of assumed this was obvious by now.
We have entire fantasy sequences that may not actually be happening (all the way back to Mercedes' Bust Your Windows back in Season 1 or Rachel's song at the end last night) and augmented reality sequences like the Telephone song last night. If you want an idea of what probably actually happened in that bathroom, it'd be something like Rachel and Charice singing a verse or two in unison a capella, but for our benefit, entertainment, and the sake of selling singles for the show, we get a performance number with full backing music.