So you are interested in buying or selling Cracker Jack items and wanted or needed to know if the item is Cracker Jack.  First you may want to check out the history of Cracker Jack.  Although that link cannot be provided, there is a Squidoo lens on Cracker Jack Toys from 1890s to present, and there is a (I think) great book on identifying Cracker Jack prizes titled "Cracker Jack Toys" (because I wrote it). 
Most toys can be either marked or unmarked; a lot of the earlier toys (pre-1970) were unmarked and a lot of the plastic toys from the 1960s were unmarked.  Unmarked could be classified as gumball, trinkets, charms, or Cracker Jack.  The gumball, trinkets, or charms are usually not well made; the silver or copper color plastic charms are a good example.  Most paper prizes were marked.
Pre-1940 unmarked prizes are more difficult to determine. Up until the 1930s Cracker Jack did buy items from Germany (Rueckheim was from Germany so I suppose he had knowledge of and possibly ties to Germany toy manufacturers) Japan, and various suppliers like Cosmos/Dowst, etc.  For example the metal game pieces used in Monopoly were also sold to Cracker Jack.
The early paper unmarked prizes are more difficult to determine, are rarer, and more expensive.  Without having a reference book, it is almost impossible to determine.  Whether you are buying or selling, over half the listing on the Cracker Jack category or that have CrackerJack in the title are not Cracker Jack prizes.