If you look at the Etymology of many English words, the US usage is actually quite often more correct than ours !

For example
Program - the mme version is a later French affectation, as the -our of colour is too.

Gotten - actually this one is a no-no.

Maths ? Now why Maths is a better contraction of mathematics I don't know. There are no applicable rules or countervailing examples I can think of. Jez's examples of genetics or kinetics don't really counr, mathematics is a long word needing contraction.

-ize endings on words instead of -ise again permitted in English English, and preferred in the OED under some circumstances.

Now the one that gets me is the American use of "momentary", which means "for an instant", not "in an instant", thus the very last thing I want to hear is that "this aircraft will land momentarily". I want it to definitely land and stay down til I get off....

Steve