That is soooo funny! We do the same thing with the "boo". My kids went all through the Haunted Mansion their first time yelling "boo" at all the ghosts!
Great minds must think alike!
The Norway ride (although not wild, and fun) is indeed dark as stated above...if he hates thunder, dark places, trolls, it might be good to avoid. Either that or save it until later in the day when it won't scare him out of wanting to go on anything else.
Best of luck and have a blast!