Jason's death, as well as Rob having to call his mom to tell her the news.
Hud's reaction to Marlena's death. Especially with him freaking out off-camera. Rob worries he might not be able to continue with them, but Hud tries to pull himself together.
The adagio towards the end of "Roar!", the music that plays over the end credits, which would have played under the scene were Marlena dies had the movie had a regular music score.
Think of everything from Clovie's point of view; it's a baby, it's lost, it's terrified, it's infested with painful parasites and it misses its mother. And to top it all off, a bunch of small creatures are trying to kill it. No wonder it was rampaging New York!