Flaw with Disapparation - Part II

I discovered another one.

Remember when Malfoy tells Dumbledore (towards the end) that he found out the connection between the two Vanishing Cabinets when Montague was pushed into it.

He says Montague "disapparated" out of it to finally escape. Now if you remember the "Order of the Phoenix", Montague is discovered very much in Hogwarts, jammed in a toilet.

Now how could he have disapparated from the Vanishing Cabinet into Hogwarts when it's not possible.

Hmmmmm....