Note that in the special case of My Cousin Vinny, Mona was introduced as a last-minute rebuttal expert witness, so the opposing counsel did not have prior opportunity to vet the expert., and moreover, was the defense counsel's fiance, so the judge granted the prosecution additional leeway in questioning her.
However, the actual attempt to disqualify her was pretty standard, and generally something many lawyers would attempt to do with experts who are either new to the expert witnessing game or have been expert witnessing for so long that they no longer actively practice the underlying occupation that originally gave rise to their expertise. (This is actually how many expert witnesses discover their calling as a witness: they get called as an expert as a routine part of their day job, discover how easy it is, and after talking to the lawyers discover how lucrative it can be.)
Despite being a comedy, My Cousin Vinny is actually one of the most accurate courtroom movies ever made.
However, the actual attempt to disqualify her was pretty standard, and generally something many lawyers would attempt to do with experts who are either new to the expert witnessing game or have been expert witnessing for so long that they no longer actively practice the underlying occupation that originally gave rise to their expertise. (This is actually how many expert witnesses discover their calling as a witness: they get called as an expert as a routine part of their day job, discover how easy it is, and after talking to the lawyers discover how lucrative it can be.)
Despite being a comedy, My Cousin Vinny is actually one of the most accurate courtroom movies ever made.