Im flying from Mumbai to Newark on a 777. I am the last seat on the plane. I would like to be able to be one of the first passengers to get out on arrival, because I have exactly 1.5 hour layover for my connecting flight. That's 1.5 hours to get off the plane, go through immigration, customs, security again and find my gate (nearly impossible). At some airports big planes are connected by at least two jetways, making it possible to leave from the backdoor. Is this also the case at Newark?
I have never seen two jetways at the front and the back at any US or EU airport. I have seen on occassion steps used by cheapskate EU low cost airlines but never jetways. So the answer is no.
Edit: apparently, not only cheapskate airlines do this. Also note "front and back" -- double jetways are not unheard of (the premium passengers get a separate one) and the A380 sometimes gets three https://youtu.be/sUZ86Z3GZiY?t=1m12s but those are all front and Newark is not A380 certified anyways so we are getting slightly off topic.
Overwing jetways are very, very rare, and as far as I know, there aren't any at Newark. Schipol is famous for having them at some gates, and there are/were a few (very limited) experiments at some US airports (one of which ended in disaster with the jetway collapsing on the wing of an aircraft).
Exit via the rear door usually only happens when disembarking via stairs or elevated buses (which would be even worse for you). Not sure if that ever happens at EWR.