Rubbish! During WWII the chances of a flak shell scoring a direct hit on a bomber such that the explosion occured inside the fuselage were incredibly small. However, if that did happen, as it sometimes did, the bomber would have been blown to pieces and would not have been able to return to base where the photo was taken. The damage you highlight is the result of a flak burst in "damagingly" close proximity to the aircraft. The peeling outwards is due to the shell splinter emerging from the the fuselage. At it's entry point on the other side you would find a similar hole where the aluminium peeled inwards.
Sounds logical .....but i'm no expert
I will not speak ..for the people think they can hear when they have not yet been taught to !