I wouldn't say its a mistake . In real life , the interior of hatches or inside of vehicles (SPGs , halftracks ) that was visible from the air was painted base vehicle color . Not much sense having all that cammo paint job and piles of branches covering your vehicle , only to have white circles or squares visible to any prowling enemy aircraft , that would ruin your day . Although you can find pictures where the interior of the hatch is lighter than the exterior , It's hard to tell in WW2 era photo if its white or just not as weathered / dirty as the outside . Personally in this scale I paint my hatch interiors a lighter color so the crew figures will stand out . If your interior was panzer yellow it would be hard to see anything of the interior unless you picked up the model to take a closer look , the white allows us to view some details even in these photos you posted
