Second appearance by Juliet Harmer as Prue, and it is rare for anyone other than the main cast to reappear.
In the scene at the auction, a man discusses mummies and Danny says that everyone needs a mummy. He is played by Patrick Newell, who had previously played "Mother" in the final season of The Avengers (1961). Brian Clemens was a main writer on that series.
At one point, Lord Brett Sinclair says to Danny Wilde: "You're no Cary Grant yourself." Tony Curtis had previously co-starred with Grant in Operation Petticoat (1959), while Roger Moore was friends with Grant.