I worked as a background actor on the show for season 1, episodes 2 through 5 (or 6?). Watched it until I wasn't in the episodes anymore. After that it wasn't good enough to keep me watching. The most interesting aspect of the show for me was viewing the final results after all the editing. It's incredible how 8 hours on set turns into 1 minute of footage!
Observations:
All of the principals were pretty cool except for Angus Macfadyen, who didn't seem to want to be there and would disappear immediately after each scene.
Kevin McNally was a laugh riot! Always joking around.
Working with Samuel Roukin was a great experience. He gave me and another guy playing American soldiers great advice for a scene when we had to escort him to a wagon and get him up into it while guarding him.
We got to smoke clay pipes in a tavern scene, and the "burning the Pope in effigy" bonfire scene.
That bonfire scene was terrible. Below freezing temperatures, standing around in mud puddles wearing short leather shoes, stockings, and jackets, for 8 hours. No bathrooms other than sneaking off behind a barn to take a leak between takes. A bunch of extras quit after that. Some older folks just walked off the set. The production did buy us all like 30 pizzas at the end though, and added warming tents on later cold days.
Canvas gaiters are extremely comfortable and warm. Especially over wool stockings.
Hessian uniforms look awesome, and make you feel awesome. Especially when you have a giant fake mustache and those leather-wrapped dreads attached to your wig. And that cool miter!
Learning Hessian marching drill from reenactors was interesting but often confusing as they insisted on bellowing German commands at us.
It is very difficult, as a civilian, to learn to march in step with 30 other guys. The officer calling cadence really helped. "Links! Links! Links recht links!" I felt a sense of accomplishment when we could do a reasonable wheel. Never fully got down the musket drill though. Luckily I was in the back row!
Muskets are heavy! And when marching with them on your shoulder, they easily knock your tricorn off your head if you don't tilt it just so.
It's fun to throw cabbage at people on stage!
If you wander into the production headquarters in a dress shirt nobody will question you if you walk up to the union-only food spread and fill up your plate with mutton and some kind of fancy fish.
Every day on set you pray to be one of the few who are temporary SAG. The difference is $8 USD/hr vs something like $30 USD an hour.
The assistant directors were the heroes of the show. They had to know just when to send which extras past the camera at the exact time. They'd be crouching around, motioning to us. Impressive coordination especially when a shot was being filmed with a moving camera.