There has always been a fair bit of doubt about this famous corps and what they wore. If you check the wikipedia there is an alternative put forward to the usual green-faced red with jockey cap image.
The variation is this: 'Their uniforms consisted of a green woolen coat faced white and a white woolen waistcoat. Their pant garment was gaitered trousers made from Russia sheeting, a hemp product. Their hats were round hats, useful in shielding their faces from the sun. When in garrison or on parade, they could bring up the leaves of that hat to form a cocked hat. Their belting was black'.
There's a painting by Don Troiani here with what the alternative might be like.
There's an 8 page pdf file on the arguments for this which is an interesting read.
At least the cartridge box plate seems to be a genuine item - as to the rest who knows?