Gavin, who plays Boaby the barman, missed rehearsals yesterday but was expected back today.
Writing on his Facebook page, Gavin said: "Well that was a good trick, crashed bike and cracked ribs half way thru rehearsals and a 6 week healing period ! Aaaaaarrrrrrrggh ! What an ---- !!!!"
But any fears that Gavin could miss part of the show's lengthy run were dismissed by Still Game co-creator Ford Kiernan.
Gavin will be strapped up and ready for opening night at the SSE Hydro on September 19.
Ford said: "We thought we were really in trouble when Gavin told us he'd broken a rib," he said. "After all, he's a really physical actor and we felt it would limit him.
"And a broken rib is really painful. We hadn't a clue what we were going to do.
"But he's been to hospital and been checked over and told he'll be okay."
A spokeswoman for Gavin Mitchell said: "Gav has cracked a rib. He's taking a couple of days to rest up but will then be back in rehearsals.
"The show and Gav's role within it is unaffected and he's looking forward to opening the show on the 19th with the rest of the Still Game gang."