Cats are so flexible that they almost seem like furry liquids. So when one cat wanted to get past a closed door, it noticed a gap underneath. After wedging its head through, the cat managed to squeeze the rest of its body through and get to the other side.
There’s a reason why experienced thieves are called cat burglars because of their uncanny ability ton get into places where they shouldn’t. If cats really wanted to threaten the human race, they could start breaking and entering homes and businesses. Fortunately cats don’t want money but just prefer food and a good petting once in a while.