The Other Slide Of Darkness - S3-E21
Continuity mistake: When Alt-Quinn tries to hand Quinn the sword, the strap from the handle in hanging down, in from of his hand. In the next shot, the handle is in the opposite direction and behind his hand.
The Other Slide Of Darkness - S3-E21
Plot hole: Quinn once again meets the alt-Quinn that he met in the pilot episode. Alt-Quinn tells our Quinn that he remembers solving the final part of the equation on his chalkboard. The problem is, there are many...possibly an infinite number of Quinn doubles in the multiverse. How could alt-Quinn have possibly known he was talking to our Quinn?