A potentially "lethal" costume could blight the performance by stars of game show The Chase on Let's Sing And Dance For Comic Relief.
Four of the ITV programme's Chasers - Mark Labbett, Anne Hegerty, Shaun Wallace and Jenny Ryan - are joining forces to take part in the BBC programme, which puts celebrities against each other to sing and dance to famous songs.
The foursome are tackling a Wizard Of Oz medley on the big night, with each of them taking on a leading role as either Dorothy, the Cowardly Lion, the Scarecrow or the Tin Man.
Although they are keeping their roles a secret until the episode airs, Labbett said the person who is portraying the Cowardly Lion will need to be careful.
He told the Press Association: "One of our costumes should be registered as a lethal weapon.
"Whoever is playing the Cowardly Lion has a tail which has already put two people in hospital!"
Hegerty said: "We never joke about these things."
Teasing their troublesome outfits, she added: "Some of the costumes are very hot.
"We've all got costumes with bits that fall off. One more than the others."
The Chasers, who are known for having to face off against contestants on the Bradley Walsh-fronted quiz show, are confident they can "carry a tune" for the stage stint.
Labbett joked he had "five years of classical ballet school" in order to train for Let's Sing And Dance For Comic Relief.
He said: "Fortunately we've all had some singing in the past, either choral or on stage, or in my case lots of singing after rugby matches in South Wales."
Hegerty added: "We can all carry a tune, which is the important thing."
Ryan said the difficulty for them is "singing and dancing together, and working out how to multi-task" and not clashing on-stage.
"We're quite fortunate on The Chase, we get to sit very still and you can concentrate on one thing at one time - the questions," she said.
"Now we're having to use our mouths, our feet and our hands and not crash into each other all at the same time."
Ryan said there have not been any major issues in rehearsals but that they are saving any "major disasters for the night itself".
The TV quiz show brainboxes are competing against EastEnders actor Danny-Boy Hatchard, group Boys Aloud (consisting of Blue's Duncan James, S Club 7's Jon Lee, 5's Ritchie Neville, Ben Ofoedu of Phats & Small and singer Gareth Gates), cast members from Holby City and Casualty, and former Strictly Come Dancing pros James and Ola Jordan.
:: Let's Sing And Dance For Comic Relief airs on BBC One on Saturday at 6.45pm.