When Teal'c uses the Zat'nik'tel on his son, it fires while in the closed position.
When SG-1 approaches the Stargate on Chulak, they quickly hide behind large rocks. As Teal'c kneels behind his, he braces himself on it. The rock easily tilts forward several inches, indicating it is a lightweight fake rock.
When Colonel O'Neill returns to Drey'auc's home disguised as a Jaffa guard (approx. 23:15), four markers can be seen on the floor (Yellow for Amanda Tapping, Red for Brook Susan Parker, Blue for Michael Shanks & White for Christopher Judge) to mark where the actors must stand when hiding behind the wall.