Authentic features of a reproduction canteen should include:

The patent label made of brass not copper.  It should be raised lettering not sunken and have the dot border.

The Brass tag is centered on the seam.

Some vendors have uesd this small brass tag for their makers mark.

It should have two different style cast pewter caps. 

One cap has straight sides the other slanted.

Caps should a molded ring not drilled and a cotter pin bent over.

The body seam should be on the inside curve. Not the convex side.

It was covered in brown or blue wool cloth.  Brown being more common than blue 3 of 11.

The jack chain should be small links and not nickle plated. 9-12 links measuring 4 inches.

The cork should be attached with a brass ring and two discs one on top and one on the bottom and 5 links of jack chain.

The drinking tube should have a perforated disc on the bottom not wire mesh.

It should have a threaded spout.