Oh boy what a Disney nightmare! Well, congratulations on going to WDW at age 6! My first visit was 24.
Now all our Disney nightmares are while we are fully awake as adults.
Alien encounter was very scary, especially for kids. I remember I helped plan my bosses Disney trip I made some notes for him with tips etc.
When the boss came back from his trip he commented how terrified his kid was at alien encounter and when they he got back to their room that day he checked my notes and they said, "Alien encounter - VERY SCARY"