Well, the trumpet (the instrument) is really far from okay (see link above for a real 17th century trumpet; here a link to another period trumpet: http://trumpetmaker.yolasite.com/birckholtz---trumpet.php ; those used in England were of exactly the same type), and the same is true of the trumpeter. He is equipped like an ordinary harquebusier/ironside trooper but I would expect special costume such as a cassock, preferably with hanging sleeves, and a hat, even with parliamentary cavalry, definitely no carbine. Equally, the cornet should wear officer's dress. And the appearance of the saddle is really quite far from any TYW or ECW period saddle I have ever seen. I cannot remember any such saddles from contemporary illustrations, nor do I know of any extant original.
But the one cockup that makes me smile is the helmets.
They've been modelled as triple-barred pots (the triple bar is the visor) which generally can be raised. However the skull has been re-inforced with metal bars so you can't raise the visor if you want to. The re-inforcement is more normally found on single barred pots, or zischagge pots which don't have a raisable visor.
Are you sure that the helmets have triple bar visors? Actually, the masters do show single barred pots, as far as I can see (scroll down):