My father's Honorable Discharge Papers also contains errors as do MANY of the docs that were issued. One of the major problems at this time, was that millions of men were going through processing and they were in a great rush to get them through. Inheritantly, many of the docs had either wrong info or info that was left off. Most of it was due to sloppy work by the discharge clerk, plain and simple.
It is not listed on my father's either, but it should have been listed too.
They screwed up the dates of arrival and departure on his too. For instance the clerk shows he departed on April 21, 1943, but doesn't show arrival until Sep 2, 1943! Doh! But, my dad fought in Sicily too which was a summer campaign. Also they do show that he took part in the Naples/Foggia Campaign, but do not list Anzio, which he was at the whole time. We even have photos. See how messed up things can get? 
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"