Because the house was located in a heavily populated area, the "surroundings" were shot in a completely different location deep in the canyons and matched up to look like one isolated location.
Ben Affleck and Matt Damon wrote the screenplay for "Good Will Hunting" in the "Dalva" house location.
When shooting at the wooded area location, a rattle-snake wrangle was required. He would shoot rattle-snakes every few hours and collect them in a barrel on set.
Most of the ghost hunting equipment was 100% authentic from working ghost hunters and was driven in from South Dakota so it wouldn't get damaged.
Heather Langenkamp (Fiona) would go back and forth from doing FX in the day for AHS: CULT and then come to set to act for us in the middle of the night.