How I'd "fix" this flick.
First of all. I think it had the wrong lead character. It should have been about The Girl. She was the only one who had any real fucked uppness in her life that needed fixing.
I would have made it about her making friends with the film making kids, the main boy not wanting her there because of what happened with his mum, but the fat kid insisting for the flick and them slowly getting to like each other.
The movie plays out as is, with the train crash and the Alien attacking and going ape in town and the evacuation.
But rather than the Alien just being angry and attacking and killing stuff seemingly at random. I'd make its motivation be, it is looking for those alien cube things the military were transporting with it and have collected up and loaded into trucks.
The movie sets up that the kids have one of the alien cubes and that it seems to float and bang against the wall of the room. I would then have that be the mystery the kids can solve when they see the super 8 video and see the blocks make up the alien ship. The kids work out that the alien isnt just going ape shit and destroying the town and killing because it's evil... it is actively trying to get home and the army are attacking it...
Oh.. and it would be the grieving Boy that is kidnapped by the alien, not the girl... Just as they were starting to like each other...
With everyone now evacuated on the edge of town, the kids realise that they need to get back in and save the Boy, and help the alien by getting it's alien cubes/ship back to it..
The girls dad and the boys dad still end up working together in their own attempted rescue mission, but this time to save the boy not the girl, in doing so the girls dad tries to make amends to the cop for what happened in the opening scene.. He doesnt even know his kid is in town. thinks she is safe. He is doing it to help the guy. Not himself.
So the kids form a plan and sneak into town as the army are doing their final big for the Alien and destroying the town in the process. But this time... rather than just dropping two of our main characters with an injury right as things are getting exciting, I'd have the group slit up. Fat kid and the other kid (rather than hide in a house). would sneak off and steal the trucks that hold the alien cubes (call back to the scene about them not being old enough to drive earlier)and bring them to a rendezvous, While the girl and the firecracker kid head to their house to get the alien cube, that after seeing the super 8 video, they now realise is part of the alien ship and is trying to return to the alien. They take the cube, release it and follow the floating cube. Using it as a tracking device to find the hiding alien and they hope, the Boy.
Now we have these kids following a magical flying object around town, avoiding the army while the other two kids have their own adventure stealing the truck with the rest of the cubs.
They find the boy, find him cocooned with all the other assumed dead residents and realise the alien was not evil and killing at random, but only taking and hiding the humans that saw him. Keeping them hidden away until it escapes... They realise that it's a "good" alien all along.. they have their confrontation...Give the alien it's cube back or maybe have it follow them with the cube, communicating they know where the rest are...
they meet up with fat kid and the truck full of other cubes just as the two dads turn up along with the army.. Just in time for the kids to open the truck, release the cubes, watch the space shop form and the alien escape in the a similar moment of awe and wonder that the film already has.. But this time it's awe and wonder at a misunderstood, scared alien going home, rather than a fuckin killing machine that just had pity on one kid because "bad shit happens"...
I'm not sure if any of that makes sense... I think the movie has every ingredient to have been really good.. They just mixed them up the wrong way.
well. that's my take.