In the original the secret passages that were always opened looked slightly different from other walls. For instance, secret passages in brick walls had two or three pixels on the left side that are darkened.

There are also the switches, like in the flames and stuff. That could be pulled off easily enough in 3d.
yea i guess ur right but the walls would be a lot more obvious and how would they make the switches reachable i dunno i think waht they end up doing for the secret paths will be cool i kno Square and they won't disapoint us =)