Another really interesting tidbit from Lauren Faust's DA page. Apparently a full on Big Mac episode was planned, but turned down in the end. It sounds like it would have been a fun one too!
I'll let you read about it above, or copy pasted below:
Big Mac is a stallion of little words. He just keeps his opinions to himself. I think he knows he's around three opinionated mares and it's easiest to just go with the flow.
We had a Big Mac centered episode idea where he was helping all three of them one day, just going along with what they wanted to keep the peace (the running gag being that his three family members were quite verbose and he spoke only with facial expressions) but finally got fed up and took off. The Apple ladies worried that they had taken his easy going nature for granted and made a big production out of apologizing and promising not to take him for granted ever again, only to find out that he went into town to get another hand- er, hoof- to help. Of course the only words he'd say were to graciously accept their apologies and promises anyway.
I thought it was cute and I LOVE non-verbal gags and acting in cartoons, but it was turned down. - Lauren Faust