How Does Your Garden Grow? - S3-E2
Continuity mistake: Miss Barrowby pretends to have just then recognized Poirot, she lowers her left hand, but has it up when he nods to her, and he has his matching hand suddenly higher too. (00:09:00)
How Does Your Garden Grow? - S3-E2
Continuity mistake: Once Japp passes him back the seed packet telling him it's empty, Poirot checks it out; in the close-up he's holding the paper in a completely different way (the side instead of the top). (00:11:20)
How Does Your Garden Grow? - S3-E2
Continuity mistake: Poirot asks Dr. Sims "So the Delafontaines, they were dependant" etc., the doctor's right hand changes position between shots, and the hand positions keep alternating between the two versions depending on the camera angle (an item suddenly appears in his hand when Miss Lemon mentions the living relatives, too). (00:26:30)