Camera Bug - S4-E10
Visible crew/equipment: After Johnny snaps the picture of Marco on the engine, when he prods Chet to go stand by the map, as the camera moves to the left we can see the reflection of production equipment/crew on the back of the squad, and we can even make out the shape of someone seated on a director's chair.
Camera Bug - S4-E10
Visible crew/equipment: When the stretcher with the unconscious teenager from the school fire is wheeled into the ER, while Roy is using the Ambu bag, just before they reach treatment 3 we can see the top of the set down the hall, near the nurses' station.
Camera Bug - S4-E10
Visible crew/equipment: At the accident scene with the truck carrying dynamite, when Roy is leaning over the driver's door, the outline of the mic transmitter is visible on the back, right side of his shirt. Then, when they're carrying the driver to the top, Johnny's becomes visible at his left side.
Camera Bug - S4-E10
Visible crew/equipment: When Johnny is driving Roy nuts by taking closeup pictures of him checking the squad's engine, the outline of the lavalier mic wire is visible on Johnny's back.
Camera Bug - S4-E10
Visible crew/equipment: At the school fire, when Johnny is administering the O2 to the teenager with smoke inhalation, the bulging outlines of the mic transmitter and wire are visible on the back, left side of Johnny's shirt.
Camera Bug - S4-E10
Visible crew/equipment: After Johnny tries to take Chet's picture beside the map, when Captain Stanley walks from the office to the back of Squad 51, the reflection of crew/equipment are visible on the back of the squad.
Camera Bug - S4-E10
Visible crew/equipment: At the start of the episode, when Johnny is taking photos of Roy in the locker room, the actor's tape mark is visible on the floor below the bench, where Johnny stands when he shows Roy the article in the newspaper supplement.
Answer: I was rewatching a few first season episodes of Charlie's Angels (1976), and in S1xE6 "The Killing Kind," I recognized the same actor. So, to finally fully answer your question, the two baseball players in School Days are played by Rod Perry and Sean Fallon Walsh.
Super Grover ★