Right crank (Drive side) on the left?
Well, you'd have a spider on both sides is one odd and annoying thing. Sheldon Brown has run the cranks in reverse on regular (non-bmx) bikes [In BMX, there is a reasonable set of options going both ways]. 

You'd also probably get a strange Q-factor as well given that the insertion depths are different for the right and left crankarms. This could be compounded if you happen to have a non-symmetrical spindle length bottom bracket.

(It should work in theory - why you'd want to do this in practice unless you were in the odd situation of having two good right crank arms and no good left crank arms is a mystery...)