Most of these asteroid impact models are also missing the secondary impact events from ejecta. For very small asteroids it's not much of a concern but anything large enough to be dangerous would kick out enough material to create a storm of falling superheated boulders. Big enough asteroids can blast stuff into orbit which then falls all over the Earth.

I also wonder if the model also accounts for vapourisation. Over the entire ocean, the effect may be negligible, but local to the impact may have made a non-trivial difference.

This particular event happened 66M years ago, it would be wild guess to include effects on land that may have or haven't existed then.