Stupidity: Why, oh why, didn't Kirk bring a communicator with him when he beamed down and found himself on the fake Enterprise?
The Enterprise Incident - S3-E2
Stupidity: When the Romulan commander discovers the cloaking device has been stolen, it's clear someone from the Enterprise took it. This is one of the most important pieces of technology the Romulans have ever developed. Rather than take immediate action to retrieve it, she inexplicably allows Spock the right of statement, giving Scotty the time he needs to hook up the device and get away.
Chosen answer: If they're in orbit, they're being pulled along by the planet's gravity well, therefore, impulse engines would only be used for minor corrections and would be "on standby" while in orbit, but not active. (Like keeping your car idling without revving the engine and creating plumes of exhaust).
Captain Defenestrator
Thank you for the info.
Movie Nut