Couldn't you get the same effect with filters?
Well, I have to say yes and no...
The thing with redscaled film is that because the film gets exposed backwards, light passes through the different filtration layers in a reverse order. This is what makes the results look weird.
In a normal situation, light that hits the film goes through a Protective layer, UV Filter, Blue light sensitive layer, Yellow filter, Green light sensitive layer and a Red light sensitive layer.
But in a redscaled film, light goes through the film in the following way:
Film base (orange), Subbing layer, Red light sensitive layer (which it gets plenty of because of the orange mask), Green light sensitive layer (which it gets very little of), Yellow filter and finally the Blue light sensitive layer.
So you get a red image with odd looking yellows and blues.
The problem with this process is that it's really hard to do properly. But when it works, it's just fantastic.