Lex wears a straitjacket in a padded cell, but these have largely been out of use in the United States for the treatment of the mentally ill for many years and have been replaced by psychiatric drugs.
When Lionel Luthor visits the Kent Farm and tells the Kents and Chloe that Lex is missing, Allison Mack's character is visibly laughing when the group is shown from Lex's viewpoint in the barn.
Lana pours Lex a cup of chamomile tea from a Thermos, however the cap is still on the Thermos, despite the sound of liquid being poured. When Lana moves the Thermos, the red dot on top of the plastic cap can be seen.
After the horse tramples Lana the horse backs into the corner. The lash of a whip can be seen caught on the stall to the left of the frame. As it is freed, the stock of the whip drops into view.
After Lana is trampled by the horse, as the camera is panning back, a microphone is clearly visible.