White triangular object caught on film - the object was not seen with the naked eye

My family and I were camping on Henvey Island approx. 3 miles due south from the town of Key Harbour on Georgian Bay, Ontario (Canada). My son was taking pictures of the sunset he did not see a craft in the sky but he did capture what appears to be a craft on our digital camera. Attached you will find 3 pictures that were taken within a period of two minutes. The last image has a white self-illuminating triangular object in front of the setting sun. My son noticed this image a few minutes after taking the picture when viewing the pictures on LCD screen on the camera back. These pictures have not been retouched or affected in any way. I have had a professional photographer look at the image to see if he could explain away what was captured with the camera - light reflection, spot on lense, bird, etc. - he was not able to explain away what appears to be some sort of self-illuminated craft.
We have looked at the photo, and we do not know what the object is.  However, our first guess is that the object may be some type of photographic anomaly.  The object does not appear to be a "solid" object, but rather just a white area in the film.  PD