The Disappearance of Mr. Davenheim - S2-E5
Continuity mistake: When Poirot at dinner asks the first question (the bathroom one), he does not have his large napkin in his vest. When he asks the second one (the bedroom one), the napkin he had for all the rest of the scene is back. (00:40:15)
Abra Cadaver - S3-E4
Visible crew/equipment: At the beginning of the episode, when the brothers chat around the central morgue table, the boom mike appears above the table, on the upper side of the screen. (00:04:55)