The end credits mistakenly list Joseph Heurtin playing Olivier Achard, rather than the other way around. The opening credits correctly list Achard as the actor.
When Maigret is looking at the notice board by the bar, three bottles of Baileys Irish Cream can clearly be seen on the shelf beside him. Baileys Irish Cream was not introduced onto the market until 1974.
The bar scenes clearly show two bottles of Baileys Irish Cream on the top right shelf. Baileys was launched in 1974 - some decades after the episode was set.