Continuity mistake: Phelps takes the tape from the recorder's right-hand spindle. When he opens the acid vat, we can see the tape he just removed back on the recorder - but on the left spindle. The tape he then drops into the acid doesn't remotely resemble the one he pulled, and when he drops it, the recorder's left spindle, where the full tape was in the last shot and where the empty reel should be, now has nothing on it at all. (00:02:50)
Continuity mistake: Over the course of many Dark Shadows episodes set in the year 1795, Countess Natalie Dupres' dark, distinct, three-dimensional facial mole changes sides from left jaw to right jaw, briefly vanishes altogether, then returns as a faint, painted beauty mark on her right jaw.
Continuity mistake: Arthur ties a rope around the battlements and descends the tower's west wall. Tony then waves a torch to signal the soldiers to attack. He's standing at the same spot Arthur left from (the rope is still tied there), but in the long shot, his torch is waving from the tower's south wall instead of the west one. (00:41:15)
Continuity mistake: "Crime Wave": Kato activates the clamps that prepare Reid's car for the flip-over that will reveal the Green Hornet's "Black Beauty." We see the clamps hook themselves to the car in close-up. But in the next, wider shot of the car turning over, the clamps have disappeared. (00:05:00)
Continuity mistake: Part 3: As you see the third "Sleeper" (a giant bomb shaped like the Red Skull's head) note the position of the monocle. First it's on its right side, then its left side, and back again to its right side. (00:14:20 - 00:15:05)