Davros's voice has changed considerably and no longer has that electronic processing that was evident in Genesis of the Daleks. Since he has been dormant for centuries, there is no explanation for it.
The remains of the Dalek/Kaled mutant that the Doctor finds on the rocks is the popular 1970s novelty children's toy Slime With Worms, made by Mattel. The original Slime toy was green, but this variation with rubber worms in it was purple.
When threatening to blow Davros up, the Doctor says to the Daleks "Sss-back off!", which sounds like he's saying "spack", a politically incorrect British slang word for a mentally handicapped person, therefore rather inappropriate for a family television program and clearly a mistake.
Although it looks futuristic, the mechanics of Davros's chair are extremely basic and requires the actor in it to be seated while moving the chair (which is mounted on rollers) with his feet. Whenever Davros moves by himself, you can notice actor David Gooderson "waddling" in his chair in order to move it. This is most noticeable after the Doctor escapes and Davros leaves with the Daleks behind him. Gooderson even knocks into the wall as he waddles away.
When the daleks follow Davros,after the Doctor detonates the bomb, the top of the dalek on the far right shifts briefly before settling back onto the bottom half, almost like a shrug.
When the Doctor is pushing Davros around, you can see lighting equipment visible in the background.
It seems the Movellans have a major design flaw with having a device that keeps them functioning within easy reach and easy to remove.
When the Daleks start exterminating the prisoners, the extras playing the prisoners are so wooden to the point of smirking on camera.