We investigate the detrimental effect of parameter mismatch on the synchronization of lasers with electro-optical feedback, whose intensity dynamics can display hyperchaotic behavior. Analytical techniques are developed to study the statistical properties of the synchronization error as a function of the various types of mismatches. The multiple mismatch case, which is of high experimental interest, is also studied and some compensation conditions allowing the improvement of the synchronization are derived. The analytical predictions are confirmed by numerical simulations and by some experimental measurements.