Other mistake: The Sliders discover the reverse-time issue when they notice that the clock on the wall is backward. However, in other shots, clocks look normal. Look carefully at the clocks on the judge's desk as the camera pans by.
Greatfellas - S2-E10
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)
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.
Plot hole: If Quinn has the timer that could be used multiple times without trouble, why couldn't he take back Remmy and Wade then come back and save the world in peril?
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: 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.
Gillian Of The Spirits - S2-E3
Revealing mistake: When the nude lady closes the door, look closely - you can see the edge of her pink bra right under the bar. (00:43:30)
Other mistake: According to reverse-time issue: In court, when Quinn looks at the clock on the wall, you can see that the clock still goes forward, despite of the anticlockwise indicators since the digits are inverted. (00:31:25)
Suggested correction: You just explained the plot that Max explained to the group. Time is moving forward to the people of that world but moving backwards for them. So the anti-clockwise movement of the hands show time moving backwards while the reverse order of the numbers shows time moving forward.
Continuity mistake: Just before the friends slide, the door behind Rembrandt and Arturo alternates between open and closed between shots.
Double Cross - S3-E2
Visible crew/equipment: When the Professor returns from the vortex and punches the guard, in the guard's glasses is the reflection a crew man holding a boom in his hands. Look closely in the right lens. (00:39:05)
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: An early nuclear warhead would be totally inadequate for destroying an asteroid 10KM in diameter - you'd need a bomb roughly FIFTY THOUSAND times more powerful than the Project Trinity bomb.
Audio problem: When Rembrandt is walking down his steps to his car while singing the national anthem, the words don't match what his lips are doing.
Gillian Of The Spirits - S2-E3
Plot hole: Quinn is unable to touch anything or anyone, yet he is somehow able to sit in a taxi cab. Why doesn't he fall through the car seat?
Suggested correction: This is a common trope with ghosts or people on the astral plane or out of phase. It's not a mistake since it's not a real life thing and it's not explained how it works (although there are some theoretical physics theories behind it). He can sit in the cab the same way he can walk on the ground and up stairs.
The Young And The Relentless - S2-E11
Visible crew/equipment: When Q notices a body face down in the pool, the camera points to pool and pans right. You can see a female crew member at a table with papers in the reflection of the glass door/window. (00:00:50)
Other mistake: Quinn is watching the video of the basketball returning from the vortex. The video shows him catching the basketball, then we see a shot of Quinn pressing the fast-forward button until he shows the basketball to the camera and says "and the crowd goes crazy!" The problem is that even though he pressed only the fast-forward button, the video fast-forwards from a point before the basketball came out of the vortex, which is impossible since Quinn never rewound the tape.
Other mistake: Quinn's alarm clock turns on, then about 8 seconds later we see the time change from 7:59 to 8:00. All clock radios turn on when the time changes, or possibly fade in slowly a few minutes before the alarm time, not a few seconds before.
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.
Revealing mistake: The doorway inside Quinn's house on ice-world is lined with snow-covered icicles. Watch as Arturo walks through this doorway; he bumps into the icicles and you can see that it is just a bunch of cotton.