Mayerling is a 1968 movie directed by Terence Young and starring Omar Sharif, Catherine Deneuve and Ava Gardner. The film is based on the real story of Austrian Crown Prince Rudolf and his mistress, Baroness Maria Vetsera, and their tragical death in the hunting lodge at Mayerling in 30 January 1889.
The following weapons were used in the film Mayerling:
Mle 1892 Revolver
Smith & Wesson Military & Police
In the final scene at Mayerling Crown Prince Rudolf uses Smith & Wesson Military & Police revolver with 4" barrel that also doesn't fit for 1889 (in reality the revolver used during the Mayerling Incident was a Gasser-Kropatschek). A smaller version in .32 caliber is also possible but less credible as the revolver seems to be large enough for K-frame.
A pair of similar looking revolvers is briefly seen in Rudolf's apartments. They seem to have folding triggers, and generally resemble Lefaucheux pocket revolvers though it's hard to say if they have open-top frames.
Mosin Nagant M1891 Infantry
The soldiers of the Austro-Hungarian army carry Mosin Nagant M1891 Infantry rifles, which is completely incorrect (Austrian infantry rifle in late 1880s was Steyr Mannlicher M1886, the predecessor of Steyr Mannlicher M1895). During the assassination attempt the shooter is also armed with a Mosin Nagant M1891 rifle.
During the street riot in Vienna some soldiers carry rifles that appear to be original Mannlicher M1895s, standing for M1886 version.
During the riot in Vienna most soldiers carry Mannlicher M1895-style short rifles. The front sights with large protectors allow to identify them as Hungarian 31M version (also known as M95/31).
Double Barreled Shotgun
During the scene of the winter hunt, double barreled shotguns are seen in hands of Crown Prince Rudolf (Omar Sharif), Emperor Franz Josef (James Mason) and Albert Prince Of Wales (James Robertson Justice).
Single Barreled Shotgun
During the maneuvers of Austro-Hungarian army field cannons are seen. They appear to be anachronistic Russian 76.2mm M1902. The barrels are extended with tubes that are most likely used for placing pyrotechnical charges.