The tabloid article says that Maxwell's head "literally exploded". As was shown in the opening tag, Maxell's head didn't explode: it pulsed and the aid fell out covered in blood, but Maxwell's head didn't explode.
Until the end when Jack dares Adam to remove the hearing aid, no one thinks that Adam is using the antique to receive transmissions from an accomplice, cuing him into the histories of the people whose minds he reads.
Jack says that Adam can only read one mind at a time. But in the next scene, Adam picks out the person holding his paycheck from an audience of hundreds. If he can only read one mind at a time, he couldn't find the person holding the check in the few seconds shown.
Adam doesn't pick up Johnny's thoughts as Johnny follows him. Granted, Adam is focused on Micki, and later Jack says that Adam can only read one mind at a time. However, earlier Adam picks up the thoughts of everyone around him.