The ability to hear and correct mistakes (wrong notes, wrong rhythms, etc.) grows with experience and study of the score in question. Young conductors often underestimate the need to study and incorrectly feel that a knowledge of principal melodies, harmonic structure, and beat patterns is sufficient.

I know of no exercises you can buy, but I can make a suggestion: When you listen to a recording or live performance with the score, train yourself to focus on one instrument's part at a time- an instrument that does not have the solo line, that is. Also, you should be aware that many recordings contain passages that differ from the score. Sometimes these are mistakes and sometimes these are "traditions" that have grown up around the score. In any case, you should listen carefully for these and discuss them with teachers and colleagues.