But at this time they're not yet in transporter range, which puts a lower limit of their distance at 40,000km. Assuming the entered transporter range a second later (and everyone forgot to mention this to Picard). This puts the lower limit of Enterprise' velocity at this point to be 100km/s, at which speed the flight from the star to the hatch would have taken almost ten days. Even more problematically, it means Enterprise would have been flying for still another one minute and forty seconds AFTER beaming Geordi and Scotty off the Jenolan. If you assume transporter range was reduced for some reason, then Enterprise' speed becomes lower, thus the trip out of the sphere would have taken even LONGER; the missing time between the moment the Jenolen wedges the door open and "The plasma intercooler's gone!" would be something like two weeks.
The real issue is that from the time Enterprise enters transporter range to the time it leaves the sphere is, IIRC, about fifteen seconds. Enterprise would have been traveling about 1.3C at the time, which would put its total flight time slightly more than five minutes, which seems to be more or less consistent with how the scene was filmed: at that speed the scene gap is reduced to something like two or three minutes between "Ensign, Set a course!" and "The plasma intercooler's gone!" Any much longer than that and the progression becomes kinda weird.
Probably much more important is the Jenolan signaling the door from a distance of 500,000km and yet still being able to fly in there and jam itself into the opening before the doors closed. If the ship is quick enough to do that--cheating the known laws of physics all the way--then scifi-movie physics probably applies and impulse engines can very well accelerate to ANY speed, even FTL speeds, as long as you've got enough runway.
