There was an error in the time stamps of the video surveillance footage outside the locker room. When Rollins shows the video to one of the boys and his mother, the video first shows a date of 2/4/2017, then changes in the next shot to 12/8/2016.
The victim is shown in the hospital 24 hours after the incident on a heart monitor. The patient is a healthy and athletic adolescent boy with a minor (albeit embarrassing & traumatic) injury. He is not receiving intravenous fluid or a blood transfusion, so the patient would not need a monitor as part of his treatment unless he had a preexisting heart problem.