A German-language film loosely based on the 1883 operetta Eine Nacht in Venedig (A Night in Venice) by Johann Strauss II. The film was also made into separate Hungarian-language version Egy éj Velencében based on the same screenplay. The two versions were shot simultaneously. The Hungarian version was co-directed by Wiene and Géza von Cziffra and used a separate cast of Hungarian actors. From Wikipedia.

A cheerful film about the Cologne carnival.

All the women adore a certain prominent singer, but one of them, a wealthy socialite, decides to court him by pretending to be just a simple maid.

Stefan is the son of the owner of a Bavarian steamship concern, which plies the Danube. During a trip to Budapest, he falls in love with the beautiful Etelka, who, unbeknownst to Stefan, is the daughter of his father's Hungarian competitor. By chance, they lose sight of each other; but as Stefan's father enters into negotiations with Etelka's father about a merger of the two companies, the children find each other once again.

During the Prohibition the US government has been just as successful at stopping drinking as they have been in the War on Drugs. Customs Officer Arne Kolk is determined to stop the alcohol smugglers at any price.

Nora, the wife of the architect Heinz Ottendorf, feels neglected by her husband. He is getting more and more engrossed in his work, but Nora, apparently a stranger to hard work, suspects that the real reason for her husband's diverted attention must naturally be another woman. Robert, the cousin of Nora's friend Marianne, has long been in love with Nora and sees an opportunity to win her hand. Heinz, for all his distractions in his work and the phantom lover he doesn't have, isn't quite ready to let Nora go. While he may be married to his work, his work is a fickle mistress: he makes a career error and this leads to near financial ruin. He begs Nora to be patient with him. Marianne, who for her part is in love with Heinz, spins a web of deceit and intrigue, which leads to Robert taking a potshot at Heinz and then eventually causing Robert to kill himself.