Continuity mistake: At the nurses' station, after Roy tells Brice that Brightweiser will be okay the two of them walk to receiving carrying their gear, with Roy holding the Biophone and defibrillator, but as they head through the doors both the Biophone and defibrillator have each turned around in Roy's hands, and now face the opposite way.
Continuity mistake: After Roy shows Brice the drug box, Roy places it back into the squad's side bay in the closeup, but in the wide shot Roy's still holding the drug box while Brice acts like his annoying self.
Continuity mistake: When Johnny is being examined by Dr. Early and Dr. Morton, Roy is in the treatment room with them, and he's not wearing a watch, but when Roy steps into the hallway and speaks to Chet he's suddenly wearing a watch.
Continuity mistake: When Early walks into the staff lounge after Johnny's surgery, and joins Roy at the table, Early's holding the cup of coffee with his right hand in the shot facing Roy, but in the shot facing Early he's holding the cup with his left hand.
Continuity mistake: While Early is examining Johnny in the ER, telling Roy about symptoms for ruptured liver or spleen, in the closeup Roy's holding up the IV bag with his right hand, but next wide shot it's held up in Roy's left hand.
Continuity mistake: When Johnny is hit by the car, the open drug box is lying on the ground right-side up in the first shot, then upside down in the second shot.
Answer: It is standard practice to wet down driveways so that they stand out in a long shot.
stiiggy