Many times, like at 1:04:32, the message "no network signal" is seen on the phone screen, but the signal meter has plenty of signal level.
At one point, the main character uses an automatic defibrillator to shock a door handle after analysing heart rhythm. Most operating theaters would have their own defibrillators with ECG and controls, not a simple one as shown in the film. Secondly, it should not shock without a shock-able rhythm - which a door knob would not have.
The Isolation Ward is repeatedly mentioned as being on the 7th floor of the hospital. But the hospital shown only has 5 floors.
Madison has a superficial wound to her thigh. The bullet is only one inch deep according to the doctor. The bullet would have been removed while in the emergency room and not left in with an open wound to continue to bleed.
The entire time Madison Taylor is hooked to her IV bag, the drip monitor never drips and the level of saline in the bag never changes.
During the final scenes, Madison runs with her sister and enters the elevator, but one of the corrupt cops enters the lift too. She had a gun on her at that time, but decides to run off again instead of shooting the guy.