Sergeant Velie hands Inspector Queen a mugshot of Jay Bonner, the mysterious person who checked into the hotel room above the murder victim. The Inspector hands it to Ellery, who reads off a list of Bonner's past offenses. But the photo as shown in the Inspector's hand was just that, a single photo with a number. It wasn't with or part of a so-called "rap sheet".
When Caesar is taken to the hotel, the group walks under an array of international flags, one of which is the modern Canadian flag that wasn't adopted until the mid 1960's.