This, the final episode, was recorded six months after the previous episode because of a BBC strike.
The woman (Mrs Taylor) sitting at the table behind Manuel while he spots the rat at Quentina's legs, is actually Andrew Sachs' wife Melody Lang.
In the kitchen after Manuel has accused Terry of putting Basil in the ratatouille, Polly slips and only saves herself from falling over by grabbing the nearby table.
In some shots a real rat was used. The real rat's appearances in studio shot scenes were pre-recorded due to fears it could run into the studio audience.
John Cleese has often remarked that Basil the Rat stands out as the best of the 12 total episodes of the series. Specifically, Cleese noted that the story does not feature any outside antagonist, other than the rat, making it the only true ensemble effort of the show. Each cast member contributes equally to the farce. Manuel also has the largest role of any episode of the series.