What's up with Mioko's speech pattern?
The dreaded TV Tropes has some pretty good notes on Japanese dialects.  The use of ora instead of ore and being used by women in particular is an element of the Tohoku dialect.  It also compares the dialect to US English 'hillbilly' accents, which matches with the subtitling.

It does not list the use of de gasu in place of desu, but the notes are hardly comprehensive.  Or it could be a personal thing for Mio5.