When Raymond comes to his aunt's room, drunk, he is seen spilling the remains of his drink in a theatrical gesture. After a cut to Ms Marple, scolding him, his glass is full again when he goes to sit down on the edge of her bed.
Aircraft of that vintage did not have ejector seats. It would be impossible for the pilot of a plane flying that low to get out of the aircraft and deploy his parachute.
When the coach driver is seen speaking into the microphone the coach appears to be traveling sideways.
As the plane flies low over the hedge, the smoke trail behind it is obviously added by CGI.
When Miss Marple is speaking with the nuns outside, when the camera is on her, there is a still figure of somebody walking but it never moves. It's obviously a still background that caught someone there.
Jason Rafiel is depicted as a German here; whereas in A Caribbean Mystery he is English.