Sir Roger Moore said that this role was his favorite, and the best ever of his screen performances.

This movie was released thirteen years after its source novel, "The Strange Case of Mr. Pelham" by Anthony Armstrong, had been published, and fifteen years after that novel's source story, "The Case of Mr. Pelham", written also by Armstrong, had been used for an episode of Alfred Hitchcock Presents (1955).

Harold Pelham's car is a 1969 Rover 3.5 Litre P5B Saloon. The blue sports car, his alter-ego drives, is a 1969 Lamborghini Islero S.

Sir Roger Moore is most famous for playing James Bond (in seven movies between 1973 and 1985). This movie was released three years before his first Bond movie, Live and Let Die (1973), but coincidentally his character says in one scene "Espionage isn't all James Bond on Her Majesty's Secret Service."

According to the website SyFy.com, "Basil Dearden, the director, died shortly after completing filming, dying in a car crash in a place that was in the exact same location that a major character dies in the film."

Two stills from the movie, one showing Harold Pelham (Sir Roger Moore) reaching across for his seat belt, and the other showing a close-up of his hand fastening the seat belt buckle, were used as part of a road safety campaign to persuade people always to wear their seat belts.

Harold Pelham (Sir Roger Moore) has a car accident. Just over a year from its initial release, Writer, Producer, and Director Basil Dearden died in a car accident.

This movie is a rare opportunity where Sir Roger Moore is seen sporting a mustache.

The movie is considered a "doppelganger" movie. A "doppelganger" is a look-a-like of a living person.

Final theatrical feature film of Edward Chapman (Barton).

Final movie directed by Basil Dearden.

Contrary to popular belief, this movie is not a remake of a television episode. It is an adaptation of the book, "The Strange Case of Mr. Pelham" (1957).

According to the website, thedigitalfix.com, the film was "a critical and commercial failure at the time; it has gone on to gain a deserved cult following.

Producer Bryan Forbes, who also contributed uncredited to the screenplay, was the head of EMI Films at the time the movie was made and released. Forbes and Sir Roger Moore also collaborated on Sunday Lovers (1980) and The Naked Face (1984).

In 1956, Sir Alfred Hitchcock was nominated for a a Film Series Primetime Best Director Emmy for the television episode Alfred Hitchcock Presents: The Case of Mr. Pelham (1955).

First of three movies starring Sir Roger Moore, which have included the phrase "The Man..." in the title. They are: this movie, The Man with the Golden Gun (1974), and The Man Who Wouldn't Die (1994), the latter being made-for-television. Moore also appeared in episodes of The Saint (1962), such as The Saint: The Man Who Gambled with Life (1969). In fact, there was a "The Man Who..." episode in almost every season of The Saint (1962).

The initials of the company conducting the takeover are E.G.O., a reference to this movie being about one personality splitting from another.

Hildegard Neil received an "introducing" credit, while the closing credits declared that Neil appeared in this movie "by permission of The Royal Shakespeare Co."

Basil Dearden performed three duties on this movie. He was the co-Writer, Producer, and Director.

The name of Harold Pelham's (Sir Roger Moore's) company was "Freeman, Pelham & Dawson". The name on the sign outside his office building read: "Freeman, Pelham & Dawson - Rugby Works Research Development".

In addition to being adapted for television in 1955 as a segment of "Alfred Hitchcock Presents", one of the few directed by Hitchcock, and only about one-fifth of the length of this movie version, the original short story by Anthony Armstrong was the basis for a British television play of the same year, and had earlier been adapted for television in 1948. All three television versions saw the story as a bizarre black comedy, rather than as a straight thriller or horror story, like this movie.

In the rear shots where Roger Moore drives his Rover at high speed & weaving in & out of traffic, there are no markings at all. That's because the M4 motorway was being extended to the Severn Bridge bordering England & Wales when the film was made.

The nickname of Harold Pelham (Sir Roger Moore) was "Pel".

As Harold Pelham (Sir Roger Moore), the character technically dies on the operating table, but is resuscitated and lives. It can be said then, that Pelham lives twice. Moore played James Bond in the spy series franchise. An earlier Sir Ian Fleming James Bond novel, and later movie, had been titled You Only Live Twice (1967).

Opening credits: All characters and events in this film are fictitious: Any similarity to actual events or persons living or dead, is purely coincidental.