Pappadimos' (James Darren) sidearm is a M1934 Mauser which he always uses with a silencer attached. In the end gunbattle, he gives the pistol to his sister, Maria (Irene Papas) so she can be armed in the end gunbattle but it is confiscated by Mallory after Maria shoots Anna. As is especially noticeable when Mallory shoots the guard who asks for coffee, it does not cycle or eject when fired.
Luger P08 Artillery
When the group is captured, SS-Hauptsturmführer Sessler (George Mikell), incorrectly named "Hauptmann" (A Wehrmacht rank, not a SS rank), by Muesel, uses a Luger P08 to torture Franklin by hitting his injured leg with it.
Enfield No.2
The commandos bring Enfield No.2 revolvers as their sidearms. Roy Franklin (Anthony Quayle) uses one to try and commit suicide, (in order not to be a burden for the team so they can complete the mission), but is stopped at the last second by Miller (David Niven). In the beginning of the film, when Mallory recruits Andrea (Anthony Quinn), he pulls out an Enfield from his shoulder holster but then puts it back when he recognizes Mallory.
Astra 400
Spyro draws what appears to be a Astra 400 seconds before he and the group is captured by the Germans but is hindered by Miller at the last second.
Submachine Guns
Sten Mk I
Corporal Miller (David Niven) and others are seen with and using a Sten Mk I in several scenes.
Sten (mockup)
Several of the commandos are seen firing what first appears to be a Sten Mk II submachine gun (modified with a shortened barrel). In reality it is actually a mockup Sten that only shoots flames. Andrea Stavros (Anthony Quinn) uses this "Sten" to kill several German soldiers in the final firefights. Spyros Pappadimos (James Darren) also uses this flame-shooting Sten and kills several Germans and then confronts their officer who also has a mockup Sten gun. (How the officer got one is unknown). The mockup Sten gun is fitted with a small flame device to represent the guns flash (in slow motion you can see that the actors aren't actually pressing the guns trigger in time with the shots). The gun is also poorly constructed: The stock is mounted in such a way the thumb does not go all the way around it due to the presence of two (gas)hoses connected to the rear of the gun itself.
Sten Mk IIS
Spyro's sister Maria Papadimos (Irene Papas) carries a SOE supplied Sten Mk IIS with an integral silencer, these weapons were dropped to Resistance units all over Europe during World War II.
MP40
The common weapon of the German Army in the film is the MP40, which is unrealistic. The MP40 was mostly issued to NCO's and other specialist troops; It was not standard issue for line troops. It is more likely they would have used Mauser rifles.
Rifles
Mauser Karabiner 98
Some Germans use Mauser Karabiner 98k rifles, but the MP40 is far more common in the film.
Mauser Gewehr 1898 (probable)
Anna (Gia Scala) is seen carrying a rifle on her back early in the movie. She never fires it nor reveal any obvious details of the type of rifle except for one scene and even then it is difficult to properly identify the rifle. In that scene the rifle reveals two trademarks of the Gewehr 1898.
Lee-Enfield No.1 Mk.III
In a brief scene a German soldier is seen with a Lee-Enfield rifle. The movie was shot in Greece with many Greek extras as German soldiers and they were presumably armed with weapons from the Greek Army stores. Both German and British weapons would have been available in Greece in the early 1960's due to their involvement in World War 2 and Britain's later involvement in the Greek Civil War.
Unknown sniper rifle - Possibly a Karabiner 98k Sporter
Andreas (Anthony Quinn) carries an unknown bolt-action rifle and kills four Germans with it when they climb the hill. After that, he never fires it again but is seen holding it several times. It is possibly the rifle is a Karabiner 98k Sporter.
Machine Guns
A German vehicle is seen carrying a Browning 1919 at one point in the movie.
Bren Gun
On the fishing boat, Pappadimos keeps a Bren gun hidden under a sail he is mending when the German patrol boat arrives. When the Germans discover who they are, Pappadimos opens fire, tearing a hole in the sail and guns down several sailors. The Bren gun is never seen after that, presumed lost when the fishing boat is smashed on the rocks.