Peter Reitan, author of the Early Sports and Pop Culture History Blog, has written extensively about the origins of the "slipping on a banana peel" gag.
Mr. Reitan has now moved his attention to the "pie in the face" gag" and he asked me for specific information on the gag's origins. When I wrote The Funny Parts, I found a number of sources that credited Weber and Fields with inventing the pie-in-the-face gag. As I recall, one of those sources was Matthew Kennedy's Marie Dressler biography. But details on this subject were not something that turned up in my research. Fortunately, online reference sources have expanded greatly in the last few years. So, now, I can explain the exact origins of the gag.
In 1898, the Broadway theatre turned out a popular melodrama called "The Conquerors." A particularly memorable scene in the play involved a smug Prussian officer dining with a French maiden. The officer attempts to force himself on the maiden, which causes her to throw wine in his face. Weber and Field spoofed the scene in a sketch they called "The Con-Curers." This time, the maiden smashes a thick and gooey custard pie into the officer's face. The rest, as they say, is history.
Mr. Reitan's research has also turned up an early car chase film, Trials and Troubles of an Automobilist. The film was produced in 1904 by Paley and Steiner, who marketed their titles under the name Crescent Films. The story involves a motorist whose reckless driving causes his vehicle to knock over an apple cart. The apple seller chases the car to get his hands on the motorist and exert violent retribution. Many others, including comic police officers, join the chase.
Mr. Reitan believes that another Crescent film, Around New York in Fifteen Minutes (1905), may have featured an early example of the "slipping on a banana peel" gag. The film, which presented a tour of Manhattan, included a scene titled "The Shopping District and What a Banana Peel Will Do." A lawsuit filed against Paley and Steiner by Thomas Edison, who claimed that the partners infringed on his motion picture camera patent, promptly put an end to Crescent Films.