“The world seems to be moving away from projectors..” Au contraire, according to the movie Pitch Perfect. The flashlight used in the Riff-off as the random song topic selector is – well, it’s probably fake, but it could be done with a pico projector packaged as a flashlight. Clearly it’s powered by HB LEDs.
UPDATE: Yes, you can play Riff Off yourself at the Riff Off page on this site.
I for one have a watch on “Riff-off-enabling pico projector” on Amazon.