This is not the slide you would want to see projected on the screen before your film started! The sound track of analogue films ran beside the images (asides from a few very early, very seldom used systems) so if the sound track was damaged there was little which could be done. Luckily it only impacted a few minutes of footage in this case!
In some cinemas this was more likely to happen. In very early New Zealand cinemas a reel of short films would move from one operator to the next and if you were the last cinema on the line the images would be worn from all the previous screenings. Some First World War newsreels were played into oblivion and no longer survive (although these did not have sound...)
In the United States of America some theatres host 'second run' screenings of films which have already been used by regular cinemas. These 'discount cinemas' often have films with slight imperfections due to their age (Titanic was screening in these budget theatres six months after its release date!)