It is a nice theory.

Do people actually believe that the continuity errors are really errors? Kubrick's use of continuity errors and breaking the line is well documented, but it also doesn't mean it's supporting the Wendy theory.

It can just be used to unsettle the audience. When you're watching it, you don't really notice the errors or the breaking of the line, but subconciously your brain does, which gives a feeling that something isn't right, even if you don't know exactly what.

Similarly, the layout of the hotel isn't possible. There's a slow panning shot through the lobby area where you can see outside through the windows, but then they get to the end of the lobby and turn right down a corridor that follows the same path. It's impossible, but you're not watching the film analysing the layout (though inherently your brain is creating a kind of blueprint).

Obviously this kind of tool is really effective in a thriller with supernatural overtones. You can create tension and unsettle the audience even in a scene with no surface tension.