To be fair, there is a Basilisk; it's just dead.
Nothing was cut down in terms of scale. Earlier concepts of the ride were indeed different, but they had much more of a "clip show" type feel. Just all sorts of random scenes that really didn't build off eachother to maximize the number of things shown on the ride. It was silly compared to what we got. The final version is much more polished. It's weird in theory that Voldemort is not included, but in execution it completely works. The Dementors make a GREAT villain. In terms of other scenes that were cut, in their place, existing scenes were extended so they make a lot more sense and flow better. The track layout remained basically the same the entire time, so it's not like we got a shorter ride. Not at all. Just one that makes a lot more story sense.
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