Check that the filename is not more than 8 characters long, only letters or numbers, no spaces and make sure that it's in a directory close to the root that also has a short name so that the overall file path is not too long.
If the error still persists change in Cart_Reader.ino:
// Change to half speed if you get an sd error or it hangs when writing
#define sdSpeed SPI_FULL_SPEED
//#define sdSpeed SPI_HALF_SPEED
to:
// Change to half speed if you get an sd error or it hangs when writing
//#define sdSpeed SPI_FULL_SPEED
#define sdSpeed SPI_HALF_SPEED