This makes it seem like it's an extra, inserted piece of information, which it is, right?

这看起来就像是额外的插入的信息，对吧？

But the door did not lock, as the man had quickly inserted a piece of iron in the lock in such a manner that the bolt could not enter.

但是门并没有锁上， 因为那人飞快地把一块铁片插进锁孔里， 插销插不进去。