When did the Germans have aircraft carriers?

The Germans did actually build one aircraft carrier, the Graf Zeppelin, but she was never finished. When this movie was made, the Allies knew of her existence, but probably didn't know how low a priority she had become.
Another interesting thing about the carrier scene is that the "German" fighters were early models of the North American P-51 Mustang (or possibly the attack version, the A-36 Apache).

Well actually, they did start construction on a pretty good sized one @ 33,550 tons in 1936 and that means that it would've been in the same league as the American U.S Navy's Lexington and Saratoga or even the Japanese Imperial Navy's Akagi or Kaga too! Also, it would have carried a pretty good number of Messerschmitt Bf-109 fighters and JU-87 Stuka dive bombers but was lacking torpedo planes like Nakajima 97 "Kate" or Grumman Avenger like the above ships had in them days. She would have been named the Graf Zeppelin had the German war industry completed her on April 1943 as they planned. Now imagine a carrier vs. carrier battle in the Atlantic this time against let's say the British carrier HMS Ark Royal and/or HMS Eagle for the control of Malta kinda like when the Japanese and American carriers fought each other to the death for control of the sea lanes during the battles of Coral Sea, Midway, and Guadalcanal!! Makes me kinda wonder a lil bit about history too! :O

Keep in mind that this movie is a fantasy so pretty much anything goes.
KS