The Night of the Burning Diamond - S1-E26
Revealing mistake: In the fight scene before the second freeze frame during the fight scene, the splicing of the film is off because we see the stationary West shifting a few inches as Midas appears and disappears on the staircase in front of him.
The Night of the Murderous Spring - S1-E27
Continuity mistake: When Dr. Loveless falls from the sill of the double window, the right half of the frame is open (the camera view being from the outside looking in). When West rushes outside to find the "body" missing, the right frame has closed itself and the left is now open. (00:08:40)
The Night of the Murderous Spring - S1-E27
Revealing mistake: Kitten bends apart the cell bars, allowing West and Gordon to escape. But when they brush against it on the way out, one of the "iron" bars gives, flexing like the rubber that it probably is. (00:40:30)
The Night of the Murderous Spring - S1-E27
Continuity mistake: In the scene after the opening credits, West's hair is brushed back from his right side. It stays that way for the rest of the scene - as he is shaving, after he is drugged, as he is shooting at Dr. Loveless, as he looks out the window at the fallen Loveless, and as he runs out of hotel looking for Loveless. While West is still outside, Gordon arrives, and West's hair looks as if has gel in it when he is talking with Gordon. After the first freeze frame, West's hair goes back to the non-gel look.
The Night of the Sudden Plague - S1-E28
Continuity mistake: West draws a chalk outline around Arte, but leaves a large gap at the top, on the right side of the figure's head. A few shots later, the gap has filled itself in. (00:43:25)
The Night of the Sudden Plague - S1-E28
Revealing mistake: In the opening scene in the saloon when Gordon takes the glass from the motionless bartender's left hand, the bartender's right hand keeps slightly moving the bottle.
The Night of the Eccentrics - S2-E1
Visible crew/equipment: West walks through the gate into the amusement park and twice passes very visible truck tire treadmarks in the dirt street. (00:09:30)
The Night of the Eccentrics - S2-E1
Revealing mistake: Tony throws two knives at West - but on the wall where the knives hit, the rectangular openings from which the blades actually emerge are delineated beforehand. Happens again a few scenes later, where slots cut in the door are already there before the knives are thrown. [Spoiler: It's inconsequential to the "revealing" error, but if you play the scene in slow motion, you can see that both times, the knives pop through from the back of the "wall." This is also how the carnival trick is performed.] (00:17:05)
The Night of the Eccentrics - S2-E1
Visible crew/equipment: When the Eccentrics outline their nefarious plan to assassinate Juarez, the boom mike shadow is moving on the door behind West and Gordon. (00:28:30)
The Night of the Eccentrics - S2-E1
Visible crew/equipment: Behind West, when he's suspended over the electrical field, you can see the shadow of the boom mike and rigging pole moving on the wall. (00:35:05)
The Night of the Eccentrics - S2-E1
Revealing mistake: Two scenes after the opening credits, West fights the strongman Titan. When Titan throws West (who is horizontally positioned on Titan's shoulders) down to the ground through the circus tent, a mattress upon which West lands is mistakenly exposed.
The Night of the Eccentrics - S2-E1
Revealing mistake: The eyes of Vance Markham's corpse move before he falls over.
The Night of the Golden Cobra - S2-E2
Continuity mistake: At the beginning of the closing scene, their private train is shown moving right next to tall green trees with large mountains directly behind the trees. The final shot of the scene shows the train in a very desert-like location moving towards the trees and mountains which are shown in the far distance.
The Night of the Golden Cobra - S2-E2
Visible crew/equipment: The shadow of a camera is seen on the couch as Artemus gets up from the couch.
The Night of the Golden Cobra - S2-E2
Revealing mistake: Indentations from West striking the board with his knuckles are seen before he hits it with his fist.
The Night of the Raven - S2-E3
Continuity mistake: Because the second one is a painted backdrop, the building across the street from the sheriff's office in the exterior shots looks nothing like the one we can see from inside the office in the next scene. (00:07:00)
The Night of the Raven - S2-E3
Continuity mistake: West and Gordon are ordered to sit on the floor to talk to the diminutive Dr. Loveless at eye level. In all the two-shots, their shoulders are touching. In all the wider angles, they're sitting a foot apart. (00:09:05)
The Night of the Raven - S2-E3
Continuity mistake: Dr. Loveless' henchmen remove Artemus' leg chain. But a few scenes later, he's shown asleep in a chair, and the chain is back around his ankle. (00:28:35)
The Night of the Raven - S2-E3
Continuity mistake: In the reverse angle shot of West's table, the plates, candles and red table cloth are all there - but the huge dish of butter has disappeared. (00:39:20)
The Night of the Raven - S2-E3
Other mistake: Balya, the Turkish representative, is killed by a knife protruding through the back of his chair. But when he falls to the floor, leaving the knife behind, there's no blood on the blade. (00:42:00)