Deliberate mistake: When Quinn comes back to the hotel room with a large stack of money he'd won at the casino, he waves it, and you can see a 1-dollar bill in the middle. He was supposed to have over $100,000, but since the crew couldn't get that much money for a brief scene, they used a stack of dollar bills. (00:35:40)
Factual error: When the missile intersects with the asteroid, and nothing happens right away, Arturo mentions to Bennish that light travels at over 186,000 miles per second, implying that the light from the explosion will take a moment to become visible. The problem is that by the time the missile is about to hit the asteroid, the light from the missile itself will have just as much lag time as the asteroid's explosion. The explosion should therefore have appeared immediately upon seeing the missile hit the asteroid.
Continuity mistake: After Quinn bumps his head, he touches the wound with his left hand and his watch is turned around so the face looking inward. In the very next shot, from a different angle, he resumes touching his head but the watch has turned around to the standard position.
Factual error: The light and the noise from the explosion are in sync to the observers on earth. However, as anyone who has been to a fireworks display can tell you, sound travels much slower than light. In fact, as far away as the explosion was, it's questionable whether any noticeable sound would reach earth at all. Even if it did, it would be heard long after the light is seen.
Continuity mistake: When the Sliders see their first bunch of Welcomers get zapped, there is a short blonde woman in that group. We know later in the episode that these people are being burned to ashes; so she is now dead. In the final scene of the episode, that woman is in the audience.
Plot hole: In the episode where the Sliders go to the world where Quinn sees himself as a child attending his father's funeral. Quinn helps his young self deal with bullies. Quinn repeatedly mentions is was all happening the way it did on Earth Prime. The flaw here is that in the Series Premier episode, they showed a picture of Quinn, his mom and dad. Quinn was a teenager in that picture, not a kid. Therefore the events in the alternate world they were visiting could not be happening the exact same way. The man in the picture is the same man shown as his father in the other worlds so it cannot be a "stepfather" that his mom remarried.
Continuity mistake: When Wade enters the recording studio to see Rembrandt, we can see him reflected in the window removing his headphones and handing them to an assistant. The camera angle changes and he removes the headphones (again) & puts them down on a stool.
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.