Trivia

In the interview with Cécile Aubry and Mehdi El Glaoui for the DVD release, she said that the fact that Mehdi hardly knew his father, who she separated from soon after Mehdi's birth, inspired her to write stories for him about lonely boys abandoned by or estranged from their fathers. This is true of this series, and also Le jeune Fabre (1973).

Apparently for promotional reasons and because no credits were listed, the impression was given that Mehdi El Glaoui sang the various theme songs of the three series. In 2009, Mehdi admitted that he did try to record them at his mother's behest, but he felt he did a poor job and convinced her to shelve them. In fact, two of them were sung by members of the boys' choir Les Petits chanteurs d'Asnières, which later on spawned the popular group Les Poppys. The first series' title song 'Belle' was by a still unknown singer, but the well-known "L'Oiseau", from the second series Sébastien parmi les hommes (1968), was performed by Bruno Victoire Polius, who as a teenager shot to fame as the lead singer of the Poppys hit single "Non non rien n'a changé". Harry Trowbridge, also of Les Poppys, recorded "La sirène aux longs cheveux" for the third and final series, called Sébastien et la Mary-Morgane (1970).

Cécile Aubry said she was asked by the production company to write a sequel to the first series, but she hated the idea of sequels, as she wanted to create something new. But the company insisted, so she talked to her son Mehdi El Glaoui if he wanted to do it again. He agreed, but requested her to set it during the summer, and include horses. This became the second series Sébastien parmi les hommes (1968), which takes place on a stud farm.

According to the band's official site, the Scottish indie pop group Belle & Sebastian named themselves after this show. The sleeve notes for their album 'The Boy With The Arab Strap' (1998) state: "Although it is little to do with the eight of us playing music, that is where the name came from, and we are grateful to Madame Cecile Aubry for letting us use the name until now and we pay homage to her work.".

Flanker, the Great Pyrenees (aka Pyrenean Mountain Dog) who played Belle, the female dog of the first series, was in fact an 18-month-old male. Directing Flanker on location was especially hard, because the dog wasn't trained at all. Lots of chocolate was used to handle him on the set. One day he ran away just to drink from a mountain stream twelve miles away, and cast and crew had to wait for his return.