Revealing mistake: While Akeem is getting his hair cut, you can see the reflection of the white character he plays in the mirror. It is quite obviously a stand-in, with a fatter face and different glasses. (00:33:45)
Revealing mistake: When in the barber shop, the elderly Jew (played by Eddie Murphy) is shown in one shot. Then when the camera changes positions, he is shown again in the background. It is an obvious double, and doesn't look anything like Murphy did in the earlier shot.
Answer: Unknown since we can't see the denomination. But at least a couple thousand dollars.
MasterOfAll