I thought the same thing but if you look closely at the flag behind Voight(Roosevelt) when he is giving his day of infamy speech it's flat against the wall so you can see that there are six rows of eight stars(or eight rows of six if you prefer) which is 48 for the 48 states. The flags look very similar. the only difference besides the quantity of stars is that the rows are straight across, not staggered like todays flag. Don't worry though, I thought the same thing at first.