"I never thought we’d get a guy of his stature to wear a period piece wool costume in 90 degree weather for 10 days straight," McBride says of casting his surprise Civil War-set final season opener. "And for no money.

This show has managed to survive — through COVID, through strikes — and we were able to still tell the story we wanted to tell and end it on our terms and wrap it up in a way

I sent him the script and he called me back pretty quickly,” McBride tells PEOPLE before explaining what happened next