I found a minor mistake with SCP-939's death message.
It states that two instances made a mess at Storage Area 9, when it is three instances down there.

I don't think this necessarily has to be a mistake, it only really is depending how you look at it. It does silently reek of retcon, but in the text all that is said is that "two of them made quite a mess", it doesn't get any more specific like, "the two in that area made a mess". Two could have made a mess, with the third still toodling off somewhere else.

For or against it, it's a two second change, as you said it's very minor.