Ok, here's a quick and easy tip for how to get a reverse vocal effect using Reason. First open up the RV7000 and patch it in to follow your sampler (NN-XT for example).

Now check out the RV7000 reverb panel, click the small arrow next to the "Remote Programmer". You should now be looking at the expanded Remote Programmer.

Now find the knob that says "Algorithm: Hall" and turn that all the way up, it should now say "reverse". And there you have it. Weird reverse vocal fx at your finger tips!