Although it airs third in the season, this episode was shot first.

The mine was designed by the show's art department and inspired by actual basalt caves.

This episode features the first-ever creature effects in the series.

The show filmed the rambler sequences with a russian arm, which was the first time they'd used one in the series.

The mossipedes are an homage to the “Trouble with Tribbles” Star Trek episode.

The song at the end of the episode is called "Calling" by Wolf Saga, the same guy that we saw performing in the Royale at the end of Episode 2.

The mossipedes were controlled by puppeteers, and the movements were supplemented by VFX.

The "northern badlands" where the episode was shot were so muddy everyone was sinking, including the rambler! In fact, Executive Producers Michelle Lovretta and Karen Troubetzkoy got stuck in the mud while driving to the location on the tech survey and it took more than eight crew members to get them out.

This is the second-most VFX-heavy episode of the season, next to the finale (which we can't wait for you to see!)