In the timeline are little indicators for keyframe locations. When you’re on a keyframe, the center box is checked. When you’re to the left or right of the keyframe, one or both of the little arrows are active. You can use those arrows to check for leftover keyframes causing motion.
To see what is moving, use one of the custom views, independent of the camera.
Or, if the camera is panning, and nothing is moving, you may be seeing parallax? Hold your finger up in front of your eye, close the other eye, and pan your head around the finger. Do you see the background shift? If this is the problem, can you parent the BG to the camera?