At one point during the fight between Ian and Ixta, the edge of the set can be seen on the right of the screen revealing the supports holding the backcloth.
The cameras used to film this episode were incapable of zooming - instead they had to be physically moved closer to their subject. This is apparent when the camera lurches violently after hitting a piece of the scenery as it "zooms in" on Autloc following Ian's arrest in the garden.
During an early scene between the Doctor and Barbara, shadows appear on the backcloth - which depicts the Aztec city - showing where it has been folded or rolled up between recording sessions.
When Ian rests his hand on a stone statue in the garden, the statue wobbles under his weight, revealing the statue to be made from polystyrene.
During his fight with Ixta, Ian backs into the sacrificial stone, which, being made of polystyrene, moves under his weight.
When Ixta is speaking to Susan about Ian's supposed death, he misspeaks when he says "seven warriors" and has to correct himself.