The version in the Anchor Bay UK trilogy boxset is apparently not the "untouched" original fullframe. There's some info on this issue at the bottom of this page.

In all of the releases by Anchor Bay, there is also some minor "enhancements" in the film itself, with a couple of frames "tweaked" to improve on the look (cleaning up some Effects Sequences - lightning strikes etc.) of The Film. The "open matte" version on the Box Set is also the newer "tweaked" version. This is a very minor issue though, but for the purists, the OOP Elite is also an option, since it's the original "untampered" version.