When a movie is advertised as a prequel and ignores continuity, it gets on my nerves. It doesn't take away from a movie's awesomeness but that doesn't mean that the nitpicking is there.
Then there is the greatest cameo of all time. It's possible because of the agelessness of said character. I'm trying not to ruin it for others but face it, most fans of a franchise will see a movie during its opening weekend. It is, without a doubt, the golden rule. You don't put it off. It's a fact of life.
If they were rebooting a franchise, no need for continuity issues from a previous trilogy but this was advertised as a prequel with a younger cast. The screenwriters just didn't do their research. Is this the studios way of retconning the horrid movie from 2006? I don't know. I'd like to think that it is. If it is the case, just redo X3 the way thatg Bryan Singer would have directed it and keep Zak Penn as far away as possible. He writes scripts that just don't have the heart that they need to have...and kills off characters that are vital.