The Santa Clause/WMG

The elves in this movie are child vampires of the Twilight variety.

 * Hence the sparkles.

The names of the eight main reindeer (Dasher, Dancer, Prancer, etc.) aren't names...

 * ...but titles, passed down through the generations, much like "Santa Claus" itself. Therefore, Chett won't be "Chett" forever.

Scott killed Santa for good.

 * The entire film franchise is a series of stories Charlie created to distract himself from the truth: His dad killed the spirit of childhood.

The original Santa killed himself.

 * The real Santa would know not to make so much noise. He made all that noise intentionally so Scott would go out and check, then when Scott yelled at him he pretended to be shocked and intentionally slipped.

The Original Santa used the Escape Clause.
He went back in time because he thought he could retire, and he chose someone who had no problem taking his job.