I think it's worth reprinting a post from Frank Ward where he explained how to spot fake CJ's.
Here is some info on the Cracker Jack sets.
1914's will say "144 Pictures" in the paragraph on back bottom, the 1915's will say "176 Pictures". The ACC# (American Card Catalog Number) for the 1914's is "E145-1", and 1915's is "E145-2".
There are many many reprints (all worthless) made for the 1915 set, and a few for the 1914's. The easiest way to tell a reprint from an original is to look at the paper type and quality. Real cards are made from a thin lower quality construction paper, very porous in texture, with a rough surface if viewed closely on both front and back. All fakes Ive seen will be made from a thin higher quality smooth surfaced modern card stock. Also the fakes will have a smooth slightly glossy or waxy surface to the front, the real cards have no gloss or waxy look to them and will not cast a glare if turned at angle to a light.
Another 100% positive way to tell a fake on the 1915's only ("176 Picture" series), is for some unknown reason, the backs on all 1915's have been printed upside down. In other words, the bottom edge of the back, is the same edge as the top of the front. I have yet to see a 1915 reprint with this upside down back.
Another characteristic of all real Cracker Jack cards, is there is no white ink on the cards. The white or light parts of the uniform is the natural paper color. Most fakes have a white ink for the white parts of uniform, that doesnt match the white border of the card. Real cards will have the uniform blend perfectly into the white border where they meet.