Jonathan Rosenbaum writes briefly on his site about Ousmane Sembène's first film, La noire de... (aka Black Girl), and mentions one of the confusing details of its history. I believe I have a bit of information to add.
The film was made in 1966, but I first saw it a few years ago in Toronto with Sembène in attendance. At the time, I didn't realize there were multiple versions of the film -- nothing was said about this at the screening, and I hadn't read anything about it online -- so I didn't take care to write down certain details that I now wish I could recall. But my fairly clear memory of the film is that it starts in Senegal. A young woman who lives there accepts an offer from a French family and leaves her relatives and friends to work in Antibes in the south of France. There's a long series of neighborhood good-byes and good-lucks. When she arrives in France, as she rides in a car from the airport to the apartment where she will live and work (as domestic help), the countryside is shown briefly in color. The rest of the film is in black and white, including the remainder of her increasingly grim days in France.
Now, when you watch this film on DVD or see the film in a retrospective, you won't see the color sequence. (As an aside: I mistakenly mentioned the color sequence in a capsule review of the DVD in Paste, because the magazine's long lead-times required me to write the review before the DVD was finished.)
The lack of this color sequence has been written about sporadically on the web -- Rosenbaum mentions it here and previously here -- usually by referring to a printing issue with the DVD, i.e. the wrong film stock was used to print the color sequence.
But I've seen no mention of a more drastic change. I was shocked to see that the DVD from New Yorker Films begins not in Senegal but Antibes with the French family. It then jumps to the girl in Senegal and picks up where I remember the film beginning. It's entirely possible that my memory is faulty, but since my understanding of the film revolves around the girl's first impression of her exciting French adventure (and the audience's, since the film is told entirely from her perspective), I don't think the version I saw began in France at all.
Since I know of no way to see the version that I saw in Toronto, I've never been able to compare it side-by-side with the commonly available one, but I'm fairly certain there are two major differences: her arrival in Antibes is in color and the structure of the film is markedly different.