When the lead characters go to France, Peter Duncan appears to be able to converse in fluent French with every local they meet. However, when Vivian is speaking French to an associate on the telephone, Peter asks John Drew whether HE can understand what she is saying.
Lundigan's character claims that he writes paperbacks. His books in his cabin and at the bookstall are clearly hardbacks.
The MI5 scientist claims that a magnet would induce magnetism in any other metal. This is untrue - only in ferromagnetic ones. He further claims that a radioactive substance would induce radioactivity in a wooden mast, which is even more nonsensical.