First of all, there were no $50 bills dated 1957. Second, the phrase "In God We Trust" wasn't added to the $50 until series 1963A, so the lack of the phrase on an older note isn't an error.
$50
...Is worth $50.
These are common in collections and sell for face value only.
A perfect, uncirculated $50.00 bill is worth $60. In any other condition is is worth face value ($50).
50 Dollars
a half hundred dollar bill is worth $50
It's worth $50.
It's still worth $50.
Us $50 :-d
.50 cents
how much is a 25 cent 1900 Dominion of Canada paper bill worth