This British-Italian co-production was edited to run 88 min. in the UK and 94 min. in Italy. Evidently Italian audiences of that era were less sensitive to six minutes of material deemed inappropriate for their British counterparts.
Once one of the "75 Most Wanted" films listed by the British Film Institute as "Missing, believed lost", the title is no longer "lost" and has been made available to the public by the BFI.
The picture of Phyllis Calvert in W.R.N.S. uniform seen her family album in the opening scene depicts her in the modern prologue of 'The Man in Grey'.
The half-million lira Johnny Lester tells Patricia Chandler the bunch of crooks want for the fake portrait of the Golden Madonna (34:11) would be about £250 in 1949 and equivalent in purchasing power to about £10,900 in 2023 ($13,000).