Rome HBO series, last post look at these two pictures

[Carus Andiae]

The mail looks darker than I've seen in real life, so it seems possible that they've touched it up with paint or whatever to give it a 'weathered' look. They did the same with the armour in Gladiator, though that of course was plate rather than mail - and appallingly innaccurate to boot. Of course, since no re-enactor's equipment goes through the rigours of months or years of campaigning, we can never be sure of how it would look.

So, to answer your question, the equipment is not accurate, but in a broader sense, it could plausibly convey an impression of a Roman soldier after a hard campaign. Of course, to be pedantic they are not cavalrymen but infantrymen on horseback.

As for the great mass of extras, yes they probably do have make-up, but more basic - mostly to take the shine off the face that studio lights create, and perhaps add a bit of 'dirt'.