Was the first Shredder a mistake for being from the cartoon?
 

He has a blue chest and faceplate, and while looked in certain light, it can appear silver (and even though it's a great figure with some good colors).... I am wondering, is Shredder ever that blue in the cartoon? Isnt he always silver/gray?

I know that a lot of companies sometimes have a marketing guide where any merchandise can ONLY be of that color until it's corrected and sometimes it comes out wrong. For example, in the Simpsons, Bart's shirt is red, but for the longest time, all merchandise was blue, cuz that's what was in Fox's book of merchandising templates.

Is this the case here?

Well, action figures typically take a 10 months to a year to go from concept to the store shelves. That's likely the reason behind the color. Since the early Shredder concept art featured a blueish metal armor. :)

am i right tho that the armor shredder is the only accurate color scheme? was he ever blue in the cartoon?

nope he was always grey