I'm somewhat curious: Could the Temporal Cold War, as shown in numerous episodes of Enterprise, have altered any historical events previously shown in TOS, TNG, DS9 and VOY? According to Trek author Christopher Bennett (and assuming I understand him correctly), if time travel from the future results in changes made to the past, those changes are only carried through to the era the time travel originated in if the time travelers return to their era, or information travels from the altered past to the future in some manner. Basically, I wonder if a lot of what we saw in ENT originally applied to the stuff set later in time.
I'm of the belief that the Temporal Cold War and Enterprise created
the timeline we see in TOS/TNG/DS9/VOY, not moved away from it. Look at "In a Mirror, Darkly" and "These are the Voyages" for proof - neither of which would be possible if the timeline had diverged from the Prime universe. Look at "Azati Prime" where we see the Delphic Expanse taking up the entire quadrant by the 26th century, yet we never saw or heard of it in any Primeverse shows or movies. Why? Because the Enterprise destroyed it in "Zero Hour"
There ARE continuity errors and retcons in Enterprise, but they are no worse than those in other Treks (see: videos in my sig for proof - the TOS Enterprise would have made Voyager's journey home in a month!) and are no more evidence of alternate timelines than any of them are.