These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Adaptation Displacement: The film was based on an obscure pulp thriller called Badge of Evil. Welles took great liberties with the plot, including relocating it to the Mexican border, making this film so much his own (and supposedly improving the story greatly in the process) that the original novel is even more obscure today.
All-Star Cast: Charlton Heston, Orson Welles, Janet Leigh, Dennis Weaver, and Marlene Dietrich, plus cameos from Joseph Cotten, Zsa Zsa Gabor, and Mercedes McCambridge. This is all the more impressive when you realize Touch Of Evil was meant to be a quick B-movie.
Executive Meddling: The film was made under budget and on schedule, but the studio still took it from Welles's control and re-edited it, cutting some scenes out and reshooting others.
Heston claimed afterward that he convinced the studio executives that he'd star in the movie only because he thought Welles was the director, when the studio only hired him to act as Quinlan (in truth, Welles and the producer had already agreed to let him direct the movie based on the Badge of Evil novel/script).
The cast is full of Fakes — Armenian actor Akim Tamiroff plays a Mexican gangster, German-American Marlene Dietrich plays a Spanish Gypsy fortune teller and neither of them affect accents either. It's not a realistic film and not intended to be one either.
Moral Event Horizon: Quinlan reaches his when he arranges for Suzie Vargas to be pumped full of drugs and then framed for the murder of Grandi whom he personally strangled just to discredit her husband.
What The Hell Casting Agency: Charlton Heston playing a Mexican. Though it must be noted that this attitude is highly anachronistic. At the time, Touch of Evil was intended as a B-Movie cookie-cutter film and not a serious docudrama about American-Mexican relations and furthermore, the notion of actors affecting accents for their roles was rare and not at all expected by audiences of the 50s, especially the genre movie audiences for whom the film was targeted.
Vindicated by History: The studio released it as a B-movie and gave it little promotion in the United States, but it became a huge hit in Europe. It's now regarded as "the best B-Movie ever made."