"Lens foot" is part of tripod collar, not lens itself, so no "fishy".
It indeed looks like one of 5D3 prototypes. No pop-up flash is one thing, but there's more.
One novelty is separate switch photo/movie mode on right to viewfinder. I don't think there were any switches like that before in Canon DLSR
Putting duct tape on name under screen does not work with me
Also screen also looks like one of size from 60D