Nero returns 154 years in the past – why doesn’t he go back to Romulus and tell them about the supernova? They would have 154 years to think of a solution or to evacuate!
Narada would also give Romulans a huge technological advantage – probably enough to defeat the Federation…

I have a couple of things to add, though (I didn’t have time to read comments, sorry if there are duplicates):

Space jump
- why does the drill have spikes? Spikes would only make sense if the drill was physically drilling through the planet.
- why did they have to drill? Wouldn’t it be enough to just launch the “red matter” towards the planet?

Delta Vega
- what are the odds of Kirk’s pod dropping exactly on that in-the-middle-of-nowhere planet/moon and run right into Spock’s cave? It’s a classic “Casablanca” scene (”Of all the gin joints, in all the towns, in all the world, she walks into mine”) :)
- was Enterprise already on course to Earth? Did they make a detour to drop him off?
- a little off topic issue: the creature’s anatomy is extremely weird and not at all appropriate – I would expect some kind of space-penguin or a walrus, not a side-headed mantis…

Supernova
- just one thing – speed of light! The blast wave cannot possibly travel faster than light. Since Milky way is 100 000 ly across, even if the star was in the (geometrically) best location (center of the galaxy), it would still take at least 50 000 years for it to destroy the entire galaxy. If Romulus was orbiting that star, the destruction would be very swift (couple of minutes) and nobody could even realize it in time (unless they predicted the explosion – like noticing the star has expanded several times :))). Otherwise, it would take years (if not hundreds or thousands) for it to even reach Romulus, so it’s pretty hard to “be late”
p.s. in the “trying to save Romulus” scene, Spock is near the blast wave, and he can see it – therefore, it’s much slower than c – so, we’re talking tens or hundreds of years before it reaches the CLOSEST planetary system…Romulus could have been easily evacuated…

Titan
- another way to hide is just to be BEHIND the moon. The only way to detect them would be to search for some kind of EM reflection on the clouds of Saturn, and that sounds pretty improbable…Of course, emerging through Titan’s clouds is much more cool :D

Nero’s choice
- what happened with that black hole? Did it stay in the Solar System? I guess it would be a worse problem than Nero :D

Cheers!

Terrible diagram below (hope html ascii works)

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– – . . – . -
– – . . -. -
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If the hole is perfectly spherical, then theoretically there is equal pressure on all sides of the hole, which would prevent collapse. The material (rock or whatever) should hold up to it, since it was already under that kind of pressure before the whole was dug.

I assume the difference here is between a solid core and liquid core planet. On our planet there is uneven force on the hole due to plate shift forces and other gravitational forces such as the moon. If Vulcan doesn’t have either of these, i say a hole to the center is possible.

Though if there is no fluid core movement, whats to create the field that stops the solar wind?

In cases like the Roman planet in “Bread and Circuses”, I guess it was the result of transplantation by the Preservers, like the Native American planet in “The Paradise Syndrome” (The Communist and Yankee planet in “The Omega Glory” may have been too. However, the other Earth in “Miri” may have been the result of terraforming and seeding by the Ancient Humanoids from TNG: “The Chase” or the result of some unknown natural phenomenon.)

As for an actual Vulcan name for Delta Vega, if that planet is indeed Vulcan’s twin planet, then the name “Delta Vega” is actually Vulcan, only anglicized.

By the way, in TOS: “All Our Yesterdays”, Vulcans of 5000 years ago could withstand a glacial climate better than humans can. Perhaps, that many years ago, Vulcan was glacial like Delta Vega, despite the brightness of the Vulcan sun.