Val rushing to save Mindy from the Graboid about to eat her in the first movie, one of the very few successful rescue attempts.
After Val and Earl come up with a plan to escape on the CAT, Val and Earl argue over who should run to the bulldozer. Val and Earl end up doing the rock-paper-scissors routine. In the end Earl wins, then Val elbows Earl in the gut and runs like hell for the bulldozer.
In the first film, after the last Graboid spits out the explosive onto Burt's pile of bombs, sending everyone scattering. Everyone tries to distract it so the now stranded Val, Earl and Rhonda can get back to safety. Burt even goes so far as to leave the safety of the rocks to get the beasts attention.
Burt: (steps on the ground to attract the Graboid) Fresh meat.
Rhonda's heartfelt (if blunt) thanks to Val for saving her from a Graboid earlier.
While the character Val could have gone without an explanation for being written out of the sequel. Always liked the written-in explanation for his absence, he got his happy ending! ...Unlike poor Burt.
Ortega: We have already contacted your partner, Señor McKee, but he was unwilling to help us...
Earl: Sure. Val married a good woman. Why would he want to die?
Mrs. Chang's sudden reversal about whether to stay and defend the town or return to China. For all her grousing about missing her homeland, she's not going to forfeit her family's hopes for a better life or take her son away from the place he's grown up in without a fight.
In one episode of the Tremors T.V. series, Nancy feels as though the danger they're facing is her fault, and apologizes to Burt, noting that while they butt heads from time to time, she considers him a close friend. Burt echoes this sentiment, and also tells Nancy that the crisis they're facing isn't her fault, and that he knows she was just trying to be a good mother and provide for Mindy.
Another moment worth mentioning is in the pilot episode, Burt whom years ago would have shot it without thinking twice; has an extremely crazy El Blanco at gunpoint, but rather than directly shoot it he shouts "El Blanco don't make me do it." shows that he doesn't want to kill his Friendly Enemy. It later turns out a device was making El Blanco hungrier than usual and El Blanco promptly ate the perp responsible.
Burt's interest is somewhat selfish, as El Blanco, being the extremely rare (and thus, legally protected) organism that he is, prevents Melvin from developing Perfection into something the residents don't want it to be. Still that Burt is interested in keeping his home and all his wacky neighbors happy as they are counts.
Graboids are highly intelligent and they grow smarter with age. Now couple that with El Blanco being by far the oldest of his kind and seemingly able to recognize individual people. Given their high propensity to eat the villains, it's implied Tyler's statement of how sometimes it seems like "that worm" sticks their neck out for the townsfolk might actually be true.