Before the concluding fight scene, Max is standing next to a vault door; a key is in the lock, attached to a keychain whose other end is attached to Max's trouser waistband. When the fight begins, the keychain disappears.
The Chief tells Max that the alarm on the conference room door sounded, but it could have been an electrical fault. However, Hodgkins found impression clay on the door's lock, something an electrical fault couldn't have caused.
Just after Professor Windish is hit with the retrogresser gun, the Chief says, "How long will the effects of the retrogesser gun last?" He leaves out the third "r" in "retrogresser"..