The Physics of Superman Returns

I'm no expert in theoretical interstellar travel, but I do know some stuff, and here's something that's bugging me about the movie Superman Returns.

The movie asks us to believe a number of things, including:
1. Superman departed the planet Krypton as an infant and flew to Earth, arriving as a small child.
2. Krypton has been demolished for millenia, in subjective Earth years.
3. Superman recently travelled to Krypton in the same spacecraft, and returned five years later.

Can you see the problem? As I understand the theory of near-lightspeed travel, the subjective time of the space traveller stretches out, so that a journey seems to take less time from the point of view of the traveller than it does from the point of view of someone who remains at the departure or arrival points (ie. Lois Lane).

Points (1) and (2) above support the hypothesis that Superman's ship travels at near-light speed. He arrives on Earth having aged only a few years, while the planet that blew up behind him has been dead for many thousands of years. However, if the ship travels at near-light speed, his more recent journey back to Krypton, while it may have seemed to him (as the traveller) to take only five years, should have allowed many thousands of years to pass back on Earth (from Lois Lane's perspective) before he could return.

Now, if we assume faster-than-lightspeed travel (positing some technique that we don't have an actual theoretical basis for yet), it is acceptable to presume that the same amount of time has passed for both the traveller (Superman) and for the stationary observer (Lois Lane). The trip that from his perspective lasted five years also lasted five years from her perspective, because he was travelling by some non-linear or non-relativistic method. If this is the case, though, then the destruction of Krypton should have taken place more like 25-30 years ago, instead of 100 times that long. Krypton's star should still be visible from Earth as though nothing has happened to it yet.

A third possibility would be if he was travelling at speeds within such a tiny fraction of lightspeed that the return journey would take only five years from Lois Lane's perspective, in which case it would be almost instantaneous from Superman's perspective. He would arrive there in virtually no time at all. This would make sense with the way the movie is made, as Superman seems surprised by the amount of change that has taken place in his absence. It's also consistent with point (3) above. If the journey was instantaneous from his point of view, he would be unprepared for the five-year lapse back on Earth.

But this possibility, like the previous one, is negated by the fact that he was using the same ship (or at least the same technology) for his adult journey as he did for his infant one. Because if this journey took no time at all, then that one should also have been immediate. Yet we see that the child has aged at least a couple of years between his departure and his arrival. Also, this would mean that Krypton is within a few light years of Earth, which is clearly not the case in the movies.

In summary, there is no way the same technology was used for both trips and all three of the premises above are true. If the journey took millenia (from Lois' perspective) the first time, then it should take millenia (from Lois' perspective) the second time, too. If it took five years the second time, then it should have taken five years the first time, in which case he would have arrived as an infant, who had hardly aged on the journey.

Sloppy.

But I liked the movie, and had a great time seeing it with Clara.