While on a shoot a few days ago I previewed my shot footage during lunch. At the time I had shot about 120 clips. While doing so I noticed that one of the clips had the incorrect thumbnail frame grab to represent the clip. The frame grab was from another clip.

If you delete clips using the media playback function on the camera you may want to be mindful that thumbnails may not correlate correctly to files.

At the time my camera had firmware 1.11