Continuity mistake: The clock on Danielle's hospital room wall reads 11:40 a.m. when she's brought in. Seconds later when the nurse leads Rembrandt to a bed because he thinks he's going to give blood the clock on that wall reads 2:30 p.m.
Continuity mistake: When Quinn has the real Duke's sword, he's pointing it towards the Duke. When the Duke tells his story, Quinn is dropping the sword down to his side. In the next shot it's back up pointing at the Duke.
Continuity mistake: In this episode the team is looking back into a slide that happened before Dr. Arturo passed away. Upon arrival on this version of earth they are showing them using a timer which they have obtained in the very episode (Exodus Part 2) Dr. Arturo gets shot and dies, and therefore couldn't have been used by them in this earlier slide.
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.
Answer: The show's creator admitted that it was the wrong Arturo.