Visible crew/equipment: After Art tells Johnny that a film about paramedics is passé, but he'll invite him to the doll movie premiere, Johnny walks over to the ambulance, and the outline of the mic transmitter is visible on the back of Roy's shirt, at his right.
Visible crew/equipment: When Johnny works on the woman in the airplane wreck and says that he'll get the radio, and then when Johnny gets into the ambulance with Angie, the outline of the mic transmitter is visible on the back of his shirt. Additionally, while Angie's mom is being loaded onto the ambulance, the outline of the mic transmitter is visible on the side of Angie's top.
Visible crew/equipment: When Squad 51 is dispatched to the car on top of a roof, it cuts to John and Roy driving in the squad as John responds to dispatch, and the reflection of the filming vehicle is visible on the squad's surface.
Bottom Line - S6-E17
Visible crew/equipment: When the guy walks into the ER with the white phosphorous burn, the outline of the lavalier mic transmitter is visible on the back of Dixie's uniform.
Visible crew/equipment: When Station 51 is dispatched to a man over the cliff, while en route there's a shot from the top of Engine 51, with the dome light in front of the camera, and the reflection of the covered camera, which is mounted on the engine's roof, is visible in the dome light's chrome surface.
Visible crew/equipment: When Roy leans over Captain Stanley after he was electrocuted, the outline of Roy's mic transmitter is visible on the back of his shirt.
It's How You Play the Game - S4-E19
Visible crew/equipment: When Johnny and Roy get the car salesman out of the car with the tiger, and when Johnny gets into the ambulance with him, the outline of the mic transmitter is visible at the side of Johnny's shirt.
The Wedsworth-Townsend Act - S1-E1
Visible crew/equipment: When Roy and John walk into the apparatus bay they stand behind Squad 51, and in this wide shot we can see that the floor area around the squad has nothing on it, but when Squad 51 is dispatched to 'traffic accident with injuries', there is now a long black tape line on the floor, near the front tire.
The Wedsworth-Townsend Act - S1-E1
Visible crew/equipment: When Squad 51 is dispatched to 'traffic accident with injuries', while en route as Johnny says "Hang a left, I know a shortcut," the shadow of filming equipment becomes visible on the hood of the squad.
Visible crew/equipment: In the treatment room, when Brackett gives the diabetic man an insulin shot, there is an actor's tape mark on floor at Dixie's feet, that we can see under the gurney.
Visible crew/equipment: When Squad 51 stalls and the guys call for assistance, when Charlie shows up and walks over to the squad, the reflection of the camera rig tracking backward can be seen in the squad's vent window. The reflection of location set lighting is also visible on the spotlight and squad.
Visible crew/equipment: After Station 51 is dispatched to the structure fire, en route Squad 51's engine stalls and starts again, then while they continue driving when the dispatcher cancels the run the reflection of the filming vehicle can be seen on the squad's surface.
Visible crew/equipment: When Squad 51 is dispatched to 'man injured', in the exterior shot of the squad while en route, when the dispatcher cancels the run the reflection of the filming vehicle can be seen on the side of the squad.
Visible crew/equipment: When Station 51 is dispatched to the plane crash, we hear Captain Stanley respond, "KMG365," and as he walks in front of the engine the partial reflection of the cameraman is visible on the windshield, right in front of Mike who's sitting in the driver's seat.
Visible crew/equipment: When Roy and Johnny load the woman who fainted onto the ambulance, the curly haired attendant gets in the back with Roy and the patient, but en route Roy is alone with the patient, and when Roy tells them to pull over we see the silhouette of the curly haired attendant sitting in the front passenger seat. Then when the ambulance pulls over, only the driver is in the front.
Visible crew/equipment: When Roy's in the ambulance with the woman who fainted, he gets permission from Brackett to leave the TKO patient, so he and John can join Engine 51 at the traffic accident nearby. When the ambulance pulls over, the reflection of array lighting can be seen on the surfaces of both the ambulance and Squad 51.
Involvement - S5-E19
Visible crew/equipment: On scene at the accident with the tanker carrying liquid hydrogen, after Chet extinguishes the fire that ignited on Johnny's back, when the fire spreads and the car explodes, the car falls onto its side and the FX stunt platform that the car was resting on becomes visible. Then two shots later that platform has vanished, as they hose down the fire.
Above and Beyond... Nearly - S5-E20
Visible crew/equipment: When Johnny and Roy get back to the station, and Captain Stanley tells them to come into the office where Chief Houts is waiting, the reflection of numerous set lighting can be seen on the squad's chrome spotlight.
The Girl on the Balance Beam - S5-E18
Visible crew/equipment: When Johnny talks to Morton about the young gymnast and the responsibility of coaches and parents, the outline of the mic transmitter is visible on the left side of Johnny's shirt.
Visible crew/equipment: After Station 51 is dispatched to the landslide, when Mike pulls the engine over on the side of the street, as Captain Stanley and Chet walk past the front of the engine, the cameraman's and crew member's legs are reflected on the windshield.
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 ★