Aging myself terribly but here goes...
I remember what had to be the first time USH had a halloween-themed event, we're talking1985-1986??...
Can't tell you if it was even labled with the HHN tag, but what I do remember was kinda of dark...
They had the tram running almost the full tour....of course after dark. In the New York sets, they had cars overturned, fires going , and "zombies" lurching at the tram. In the Little Europe part, they had the monsters coming around, and as kind of a cool effect, they had "bodies" strung above the trams as they drove through certain areas. However they were low enough they''d scrape across the tram celing, then "Flop" down between each car as it passed, and bounce back up to scrape along the next car.
From what i heard, their was a tragedy during one of the nights-It may have been while we were there, but I dont know. On the way up the "physco-path" towards the house, various 'things' would be hiding in the tall grasses/bushes along the tram route and jump/reach out towards the cars. What i was told is one of the actors over compensated his jump, and was caught between tram cars, struggled to get free and wound up under the cars, run over. Supposedly his screams were real.....
Urban legend, maybe. Morbid? Yup.
BUT the scariest thing we heard all night was the band they had playing in the wild west stunt show-Ready For The World. I think i heard "Oh Sheila" three times walking around that night.....