Factual error: When Grace is fighting the controls of the C-5 cargo aircraft there is a shot of part of the instrument panel. Among the items on the panel is a switch labeled "tail rotor quadrant." The C-5 does not have a tail rotor. Helicopters do. (01:35:00)
Factual error: When Grace first shoots the Rev-9 Terminator, she is using a Winchester Pump Shotgun with a long magazine tube. She however fires 13 rounds at the Terminator, while the shotgun is only able to hold a maximum of between 7-8 shells in the magazine tube.
Suggested correction: Sarah is very skilled at fighting Terminators. She receives the coordinates but knows that many other real-world factors may impede her progress to those coordinates, so she makes efforts to prepare for that. Also, the coordinates that she received for the Rev-9 may very well have told her to fight it on the bridge because the T800 who sent those coordinates knew that Sarah would also then be able to rescue Dani and Grace, and eventually meet up with him as a result.
I'd say the real reason Sarah is on the highway to fight Rev-9 is that she followed it. She misses the moment it arrived (from the future), she follows it to the car factory, but she misses it again, then she finally catches it up on the highway.
It is explicitly stated by the T800 Carl that he was sending Sarah the coordinates of where the terminators would appear, because the arrival would create a space-time wrinkle he is able to measure ahead of time. There is no indication he can predict the future events and send Sarah coordinates of places to be other than that.
Epigenis
Suggested correction: Sarah's truck can be seen in the background when Grace arrives. Grace doesn't look like any Skynet Terminator, and the time bubble she arrives in is different to the ones in T1 and T2. We can infer that Sarah followed Grace from her arrival to the bridge in an attempt to understand what was going on with the new time travellers before intervening.