The fact that the supporting affidavit is not attached to the warrant when the warrant is executed does not itself invalidate the warrant, though, of course, there had to exist good cause for the warrant and a sufficient evidentiary basis to support it, and if it turns out there was not, the wararnt my later be challenged on that ground. As to whether they could open the safe or not, that depends on the terms of the warrant; if the text of the warrant authorized or would support them doing this, then they could.