The factory steering wheels and aluminum windshield frames are dead giveaways that it is a Backdraft. Like mentioned before, the 92" wheelbase is very hard to detect (great job Backdraft). I have replaced both the steering wheel (with Motalita) and windshield (chrome plated) on mine for a more authentic look. The license plate can be notched a little both top and bottom and it will fit properly instead of covering the handle.
A very distinguishable feature that can't be seen, but can be felt is the great BMW suspension and rear end. Anyone that has ridden in my car that has a different Cobra makes comments about what a great ride the Backdraft has.