Barker and Mitchell were last minute replacements because some of the original cast couldn't make it to the recording.
A lot of things changed over the course of the season so far.
Due to not having portraits when Maya was ready to edit, Memey decided to use pictures until the portraits were ready.
Since Maya's editing software stopped working after Episode 2, Memey got Map to edit for the rest of the season.
Portraits changed on Episode 6 due to Mitchell not having a SonicTommy portrait / not giving a ref to him, so Dewott became the new portraiter with Mitchell's portrait just being bacon. (Which was his skin for the season)
Starting Episode 7, a new intro was put in due to the old one being made by Maya.