First of all there is the added character of the Marschall. He is a vigorous and virile officer, and he is suffering as much from the separation as the Marschallin. There is a touching sequence where everybody else on the front is receiving love letters, while he is left to ponder the lace wristcuff from the shirt of his rival.
Because of the introduction of the Marschall as an acting character we have epic battle scenes and even a thrilling "race to the rescue" sequence where the agonizing Marschall rides home to find out what is going on in the marital bedroom.
Along with the figure of the Marschall four marches are added to the score. This addition fits in very well. The very overture of both the opera and the film starts with a militant fanfare expressing the masculine urge, followed by a theme expressing a soft, swirling, yielding feminine response.
We miss the profound solo arias of the Marschallin, but there is a flashback of her at the convent where at 16 she is fetched to marry a man almost unknown to her. Suddenly her brand new husband is ordered to the front before their wedding night. Although Der Rosenkavalier is a comedy, there are moving scenes of solitude, frustration, and sadness.
Octavian has been changed from a trouser role to a regular male role, played by the androgynous Jaque Catelain.
The "play in the play" scene is one of the best in the film. The protagonists witness the caricature performance in which the "Rosenkavalier" story is parodied for all to see.
The Court Commission on Virtue and Manners is another funny addition (not without sinister implications, though) to the film, an instance of visual comedy.
As is the scene of the waking of the soldiers asleep in the hay.
In keeping with this comedy is also the scene of the lawyers. Baron Ochs resorts to extreme measures to pressure Faninal into accepting a marriage contract with ruinous financial conditions.
The interpretation of Baron Ochs interpreted by Michael Bohnen is consistent with the emphasis on farce. This talented comic singer-actor was known to be Strauss's ideal casting for the role of the Baron. Let's not forget his extended waking-up pantomime and his mad dance of joy.
"The stronger the villain, the stronger the picture", stated Alfred Hitchcock, and certainly in this film version the Baron is the most memorable character. We believe in him because he seems to be at home as himself, enjoying himself thoroughly, even though nobody likes him. In comparison with him all others seem ill at ease. We can compare Michael Bohnen in this role of an incorrigible roué with Erich von Stroheim, "the man you loved to hate". Stroheim and Lubitsch would have been the ideal directors for a film adaptation of Der Rosenkavalier.
In the film the fate of Sophie mirrors that of the Marschallin. She, too, is called from the convent at 16, in her case to marry the oafish and impoverished but certifiably blue-blooded Baron Ochs. Der Rosenkavalier offers an account of her introduction to the world of disappointment. We first meet Sophie at a garden party where the newly minted aristocrat is marginalized and literally excluded from the circle. Only Octavian reaches out to her, and it is love at first sight, although they do not know one another's identity yet. The Rosenkavalier scene in the film is both recognition and revelation.
The most heartbreaking disappointment for Sophie awaits at the final garden party where there is a masked date. Sophie then realizes that Octavian has been expecting to meet the Marschallin instead of her. Deeply regretful, Octavian with all his powers of wit then turns the tables in the elaborate final manoeuvre.
The lovers have many obstacles to overcome. Neither one is free: Sophie is now bound by a marriage contract and Octavian must await the Marschallin's blessing. The resolution comes in a spectacular final garden party. With much intrigue and several masked encounters, elaborate dance numbers and a cast of hundreds, it replaces the entire third act of the opera and represents the most extensive change in the film plot. Along with the real locations on which the film was shot.
The film concludes with a triple happy ending. Not only do Sophie and Octavian come together as a couple, so do the Marschal and the Marschallin in their reunion, as well as Annina and Valzacchi, the schemers. The narrative transcends feelings of vengeance. The only one left out is the Baron who wanted to win everything but lost all.
The opera is the definitive version of Der Rosenkavalier, but this instrumental arrangement has its rewards, as well. The amusing leitmotif of the Baron works well on a film soundtrack. The instrumental version of the special bel canto aria of the first act remains wonderful even out of context. And the non-singing arrangement of the aria of the three sopranos (a celestial one that Strauss wanted to be performed at his funeral) is divine even in this abbreviated instrumental form where pure music takes over.