As Winthorpe and Valentine are discussing what is to be done, Ophelia is watching TV. A brief clip of the costume ball is shown, just before the newsflash.
Similarity of plot (both involve a retired European jewel thief accussed of stealing again and the theif's attempt to clear himself; in both films the true thief is a woman close to the former thief; the connection is made plain with the spoken line, "Set a thief to catch a thief"