erra is new jersey
Missurah is Missurah
don't mix them
As a Chicago native, I know that there isn't an "r" on the end of error wherever Hawk Harrelson is from. I suspect there also isn't an R at the end of Missouri there, so it's plausible that those two forms exist together in some American dialect.
But yeah, I should know better: my #1 complaint about people trying to fake a Chicago accent is that they remove the final "r" of words, because that is something that happens in east coast urban working class accents but not in midwestern urban working class accents. But I think "r" drops off in the rural south too.