Wrong date in certificate
Very few places look at certificates when looking at applications.  Certified transcripts are considered the authoritative source.  If it's correct in the transcript, then that will be fine for the application.  If they wish to validate the transcripts, they will contact the institution directly whose records will match the transcript, not the certificate (almost certainly).

As for correcting the certificate, some institutions allow you to contact their registrar's office and request a re-printing of the certificate.  If it has been many years, the biggest problem is often that the Provost/Chancellor, etc. of the institution may have changed, so the signatures may not be the same as when you were issued your degree.  The specifics depend on institution.  There's no harm in calling or emailing them and inquiring.