Shooting on the second series of the drama, which stars David Tennant and Olivia Coleman, has drawn criticism after a camera crew was seen filming on a "dangerous" and "unstable" cliff in Dorset.
Photographs taken of the crew suggest they were only inches from the cliff edge despite several warnings from the local coastguard that rockfalls and landslides were possible.
Some 400 tonnes of rock fell on to the beach from the cliff, where they were filming as recently as February.
A spokesman for the Portland Coast Guard said: "It can go in an instant and doesn't give any warning. It is definitely not wise to go near the edge."
Another coastguard rescue officer described the crew's actions as dangerous and "really stupid".
But the drama's producers have defended their actions, saying they take health and safety very seriously.
For the moment the only deaths they are planning are on-screen ones.