James Arness (Garby) served in World War II and is the most decorated of the actors in the film. He received the Bronze Star, the Purple Heart, the European-African-Middle Eastern Campaign Medal with three bronze campaign stars, the World War II Victory Medal, and the Combat Infantryman Badge for his service.
Douglas Fowley (Private Kippton, he of the continually lost false teeth) served in the Navy in the South Pacific in World War II, and lost all of his own teeth in an explosion aboard his aircraft carrier during battle.
The white "card suit" stencils on the sides of the soldier's helmets in the film are accurate. The World War II 101st Airborne Division used the different suits to identify their three parachute infantry (diamonds, hearts, and spades) and one glider infantry (clubs) regiments. A white "tic" at either the twelve, three, six or nine o'clock positions around the suit indicated Headquarters, 1st, 2nd, or 3rd Battalions, respectively. The soldiers in this film wear the club suit of the 101st's 327th Glider Infantry Regiment, with a "tic" at the nine o'clock position, indicating they belong to that regiment's 3rd Battalion.
Screenwriter and associate producer Robert Pirosh fought in the Battle of the Bulge as a master sergeant in the 35th Infantry Division, which helped relieve the 101st Airborne at Bastogne. In the spring of 1947, he traveled back to Bastogne to do research for his screenplay and found his old foxhole outside the town of Harlange. The foxhole still had the pine branches Pirosh had piled on top to protect himself from shell bursts, and contained an empty K-ration box.
Twenty veterans of the 101st Airborne, who fought in the Bastogne area, were hired to train the actors, and were also used as extras.