Continuity mistake: Frizz and Nug switch colours in a couple of episodes of the show, and Nug has Frizz's glass colour too.
More mistakes in The Dreamstone
Frizz: Nice view of the sea, Sarge. Two little islands. And one of them's coming towards us. Now it's rising up out of the water, sarge.
Nug: And it's got one eye... Aaaaaaaargh!
Frizz: Aaaaaaaaaargh!
Trivia: Urpgor falling down a cliffside twice is a reference to the Wile E. Coyote and Road Runner shorts.