1. Sometimes camera bag becomes especially heavy for no reason.
Time to buy a lighter bag and leave the long lens at home
2. Sometimes a second shadow appears in the photo.
Problem with natural light.
3. Sometimes tripods shake and move to a different position by itself.
Time to upgrade to carbon fibre type with higher loading capacity.
4. Sometimes camera flashes by itself for no reason.
Flash test fire button must be loose.
5. Sometimes there are green eyes instead of red eyes in the photos.
Sensor must be dirty.