Continuity mistake: At the hospital, when Cruz talks to Herrmann while he still has the oxygen mask on, Herrmann's hand keeps switching between clutching the mask on his face and resting at his side. (00:38:45)
Where the Collapse Started - S4-E22
Visible crew/equipment: After the paramedic locates the injured firefighter, the shot cuts to the outside and the camera operator's shoulder can be seen in the lower left of the shot.