Sometimes things go wrong and the results might be worth keeping. Here a few of my recent favourites:
In the above photo, I accidently put the camera in multi-exposure mode and took some long exposures from different angles. The Pentax MZ-S is a professional 35mm camera with all the settings conveniently available as switches on the outside of the camera for quick adjustments, yet it also means that you do need to check the settings when pulling the camera out of the bag.
If you work without tripod and put the camera on the railing of a bridge for a long exposure or night photography, make sure it is not a train bridge! I had put my camera on the railing of Norra Järnvägsbron in Stockholm to photograph the City Hall for this eight second exposure and the moment I released the shutter a long train came by.