The opposite problem of having 25 year old actors be teenagers?

He looks too damned young, the actor was about fifty when this was filmed and compared to a hundred fifty is VERY young, You could fit my entire life just inside the difference.

really old actors are hard to find or might die during filming but it would be a lot less of a stretch if the actor was 70 or 75. Fifty is just too young to portray a 100 year old even with the aging makeup.