I too was convinced the shield would be white, as shown on the box (not sure about the saddle, like you say it isn´t visible on the box´pictures).
But it turned out to be black, like the saddle.
I´ve asked around with some Color Collectors to know if there were perhaps several versions of the set, but the answers I got all point to the black shield and black saddle. (I still have to get answer from another reknown Dutch Color expert)
I know the white shield came with the famous Kaufmannszug 3660 (released 1979), I meanwhile assume also with set 3661 (released 1978) and probably 3703 (released 1978) as well. The Color Tournament-Knight Set 3624 was released with a gap of 2-3 years, in 1981, so that might perhaps explain the change...
When I´ve time I´ll take pictures for Klickywelt Datenbank-Setinhalt (still have to take a lot of pics from new custom-figures too).
But I can´t really promise the bags will still be sealed by then... you know me, I´m The Belgian Ripper
I must add the set I got has the 2 Color-klickies with moveable hands, so it probably is from a production batch later then 1981?