Spot the differences in Rhett & Link film

Comedy duo Rhett & Link - who regard themselves as 'internetainers' and have created over 500 web films - wrote, directed and starred in this film for bedding manufacturer Carpenter Co's Sleep Better initiative.

The two sides of the screen show almost identical performances of the same song, but with some differences. The viewer is challenged to spot those differences and submit their estimate at the total number here for a chance to win $4000 and some Sleep Better products.

The full rules (eg small differences in choreography don't count) can be found beneath the video here and the infectious song is available to buy here.