The shards inside will be extremely sharp and some of them very tiny. You don't want any escaping! Before you finish, cover the holes on both sides with PVC or similar sticky tape so that no shards can escape. (Or if it makes you feel better about your poor old drive, you could use a sticking plaster!)

It's still possible that small shards could escape between the circuit board and the metal shell so continue to treat the drive with care. To avoid this you could unscrew and remove the circuit board before starting.