Factual error: Adam Beck says "Kill the lights, unit one." They just don't shut off a main breaker but they cut the main wires. Then shortly afterwards the lights are back on again. It would have taken an electrician hours to replace the cut wires to the power. (01:44:25)
Factual error: Chris Sabian tells them to "Cut the electric, cut it now." Shortly afterwards Danny calls Chris on a cordless phone. Cordless phones only work if the base unit is powered, so Danny wouldn't have been able to make the call. This happens a few more times when they turn the power on and then off again. (01:17:40 - 01:20:30)
Answer: According to IMDB.com, Paul Guilfoyle did play Nathan, though he wasn't credited for the role.
Xofer