Revealing mistake: As Kai's squadron fly across camera, it cuts to Kai in his cockpit with his shadow on his right. But as the camera pans around to get a side view of him, his shadow moves in the other direction revealing them moving the light with the camera. (00:01:55)
Continuity mistake: Kai is flying his dragonfly space craft towards an enemy ship in the beginning with his wingmen as they sing. Kai's shadow is cast on the wall behind him on his left, but when the camera cuts to a close up of him, his shadow is suddenly on the other side. (00:02:05)
Audio problem: As the Fore Shadow is charging up its blast each time, when first shown it makes a high pitched shrieking sound as the energy spreads across The Web of cables fanning out from it. However as the battle continues, this sound effect becomes very inconsistent when it plays in correlation to the energy blasts charging up on the ship. (00:02:15 - 00:03:20)
Continuity mistake: His Shadow's ship, The Fore Shadow, begins to blast the Brunnen-G planet and the shots hit the surface causing massive instant damage seen and heard from space. Each hit charring the ground. When the camera cuts back to the planet a few shots later as the ship continues to fire, the destroyed areas of the planet from before have all moved around, with the giant char marks being inconsistent in where they landed. (00:02:25 - 00:03:10)
Continuity mistake: Kai orders his squadron to bring up their stingers on their bug ships, and in a side angle shows them curling up like a scorpion stinger. It then cuts to a close up of one stinger opening and it suddenly changes shape a little. In the side angle it looking more like a shark head with a visible hump on the bottom side, to being almost a perfect round football like shape in the close up. Also the space gas around the ship changes from green to white between shots. (00:02:35)
Continuity mistake: Kai tells his squadron to have good luck and his mouth is hanging open a little after he says that. Then it cuts to a close up before he says "very very good luck" and suddenly his mouth is fully closed before he speaks. (00:02:50)
Continuity mistake: As Kai's squadron swoops in to fire their 'stingers' at His Shadow's ship, only 3 of the 6 are shown flying at the control pod. But in the next shot as they fly past it with their stingers hitting, it's 4 of them flying away. (00:03:00)
Other mistake: As Kai's squadron are approaching The Fore Shadow, the ship begins to fire its massive web like plasma waves at the planet, and fires over and over continually. Except in close up shots as Kai's squadron are flying around it. Like it completely stops firing in closes ups, though when cutting away suddenly blasts are close enough to it that they would have been coming out during those close ups. (00:03:05)
Continuity mistake: Kai and his squadron fire their stingers at His Shadow's ship, and it shows the missile like things heading towards part of it with large cable like structures interconnecting the pieces. When the angle cuts as they hit, the explosions appear in huge size instantly and the positions of these cables change quite a bit. (00:03:05)
Audio problem: As Kai is the last fighter left, he flies towards His Shadow's control pod on his ship to ram into it kamikaze style. As he's approaching and it cuts to the control pod dome starting to close, you suddenly begin to hear the alarms going off inside The Fore Shadow ship. And it's heard from inside Kai's fighter, and from outside from camera angles. And then when Kai crashes into it and flips out inside, you still hear the alarm inside the ship at almost the exact same volume as heard from outside. It's almost quieter even. (00:03:50)
Continuity mistake: When Stanley is sleeping in his bed as the computer starts to wake him up, his head is turned left under his covers. When the camera cuts to a close up, his head is turned right. (00:06:35)
Continuity mistake: In the prisoner transport ship after the crew wakes up, one goes down a ladder to check on the prisoners to find Number 11 freeze dried. In the first shot, the dead prisoner's arm is casting a shadow to the left, but when the angle changes the shadow is to the right of his arm. (00:09:05)
Visible crew/equipment: After the cannibal woman spits on the guard as he walks through the prison transport ship, he comes to a long haired guy. But as he comes onto screen you can see the end of the set piece for the ship with the walls of the shooting studio visible. Then when the camera cuts to another angle it shows the guard still has a lot of ship to walk through. (00:09:25)
Continuity mistake: There are four other nuts lying on the ground around the hole at the feet of the 790 Robot where Stanley had been trying to throw them into the hole. When talking with the prisoner transporter woman, he throws another nut at the hole and makes it in, and in the close up of the hole the nut that was the furthest to the right vanishes while the other three remain in the same spot. (00:11:40 - 00:13:00)
Revealing mistake: In the hanger dock where Stanley is working, there are some purple lasers in the background going up and down like a security gate. But during their animation for a moment, they suddenly jump back to previous positions as the loop in the animation is not lined up correctly. (00:11:40)
Continuity mistake: Stanley throws a metal nut at a 790's butt and when it hits, it shows it bounce off towards the right. When the camera cuts to the hole at the robot's feet, the nut falls into frame going left. (00:11:40)
Continuity mistake: When Stanley is trying to bounce nuts and bolts off a 790 Unit's butt into a vent like hole in the ground, it shows the robot standing with its feet next to the hole and aligned with it nearly centered perfectly. When it cuts to a different angle from a distance, the robot is now standing a bit to the right. Also the hole appears to change. (00:11:40)
Continuity mistake: While Stanley is at his post as a guard, a woman comes onto his screen requesting clearance for a prisoner transport dock. Stanley puts his hand up onto his mouth thinking, but when the camera cuts to an angle showing the front of him, his arms are both suddenly down at his side. (00:11:55)
Continuity mistake: After the Prisoner Transport Line Major gives the wrong access code, Stanley puts his arm up and rests his hand on the table next to him. But through the rest of their conversation his arm goes from this position to down by his side repeatedly depending on the camera angle. (00:12:25)
Continuity mistake: As the current host for His Shadow is dying, the Clerics are rushing him towards the temple structure for the Divine Predecessors and towards the foremost column to perform the transference operation. In the shot showing all the columns as they rush towards it, the bottom of the closest one is normal like the rest. When the camera cuts to a side angle as the Clerics reach the base, there are suddenly doors and curtains there with three other Clerics standing at the ready. (00:14:20)
Answer: From what I'm seeing, the answer seems simple. The robotic heads allow the control of the body they need. However, no mater how advanced you make a robot's body, it will never quite be as flexible and versatile in it's movements and actions as a flesh and blood human body can be in most cases. And if they do put the effort into creating a robotic body with the capabilities they need, and be durable enough to last... it would cost a lot of money. The Cluster has a large influx of constant prisoners that they use for feeding the Lexx and other needs, so human bodies are easy to come by and in vast quantities. Them simply producing robotic heads with the ability to interface with the human nervous system and placing them on the decapitated bodies of expendable prisoners is a hell of a lot more cost effective and easier to do with the technology they have. It's just a cheaper, more effective option for them to have thousands fo 790 Units in production and use without the cost of manufacturing a fully functional and durable robotic body for them.
Quantom X ★