No way did a 5 week old chick lay an egg so I would have to agree that one of your "road island reds" is actually an Americana (easter egger). As far as I know RIRs only lay brown eggs. Definately look for face fluff as a sign you actually have an Americana as they are bearded. Even if neither year old hens are bearded, one of them had to have layed the green egg which rules out RIR and strongly implicates Amaricana as the breed.
Was it a bright pastel green or a really pale almost white green? And was it bluish green or green green?
Was it a bright pastel green or a really pale almost white green? And was it bluish green or green green?