Visible crew/equipment: When Station 51 is dispatched to The Boat explosion, just after Captain Stanley responds, "KMG365," as he walks past the camera to the engine, we can see the open top of the set at the rear corner of the apparatus bay.
The Lighter-Than-Air Man - S5-E8
Visible crew/equipment: When Station 51 is on the scene with the overturned truck carrying insecticide, that's causing toxic smoke, Captain Stanley asks dispatch to identify the toxicity of trimelanide, and three shots later a crew member walks onscreen from the left, right behind the overturned truck, then realizes his mistake and backs away.
Visible crew/equipment: While en route to the structure fire, Mike is driving Engine 51, and seated backwards in the jumpseat behind Mike is Marco, who's wearing a helmet and his turnout, but in the shot from the POV behind Mike, we see the reflection in the rear-view mirror of the grey haired crew member, who is seated facing forward behind Mike.
Visible crew/equipment: During the structure fire, when Captain Stanley uses the HT and says "Engine 17, you can pump to Engine 51," in the next shot a second cameraman carrying a handheld camera is visible between Engine 17 and Engine 9, as he's shooting footage. He's visible again three shots later, standing beside Engine 17, and once again right after they lower the ladder through the hole in the roof.
School Days - S2-E14
Visible crew/equipment: When Squad 51 gets pulled over to help the guy with a snake on his stomach, just as Johnny reaches over to take the broom from Billy, the outline of the lav mic transmitter is visible on the back of Johnny's shirt.
Visible crew/equipment: When Roy, Johnny, and Karen are waiting outside the treatment room with the elderly patient, with Brackett and then with Dix, the outlines of the lavalier mic transmitters are visible on the left sides of Roy's and Johnny's shirts, over their belts.
Visible crew/equipment: When Johnny and Roy are speaking with the Battalion Chief in the apparatus bay, about who could have stolen the money, when they walk forward there are two tape marks visible on the floor behind them, where they were just standing.
Loose Ends - S6-E12
Visible crew/equipment: When Dixie visits Brackett in his hospital room, he insists on seeing the little girl from the accident, but she convinces him to get back into bed. Then as he says "Alright, but later I want to see her," the actor's tape mark is visible on the floor near the second bed, where Dixie stands as Brackett gets back in bed.
Visible crew/equipment: After Johnny and Roy are called back into the home of the young couple, who were issued the fire-code violation ticket, when Roy is on the Biophone with Rampart, the bulging outline of the mic transmitter is visible at the left side of Roy's shirt, just over his belt.
Fair Fight - S6-E5
Visible crew/equipment: At the cave-in site with the trapped men, when Johnny is up top and also when he's being lowered down to the men, the bulging outline of Johnny's mic transmitter is visible on the front, left of his shirt, right above his belt.
Fair Fight - S6-E5
Visible crew/equipment: When Roy and Johnny are at Rampart after their third run to the battling couple's home, the outline of the mic transmitter can be seen on the front, left side of Roy's shirt, over his belt.
Visible crew/equipment: When Johnny is kneeling on the sidewalk beside the woman who fainted, the outline of the mic transmitter can be seen at his left side, above his belt.
Visible crew/equipment: When Roy and Johnny are with Johnny's friend, the stunt coordinator, trying out the new gear, the outlines of their mic transmitters are visible on the left sides of Johnny's and Roy's shirts, above the belts.
Bottom Line - S6-E17
Visible crew/equipment: A man walks into the ER with a white phosphorus burn on his arm, and when they wheel him into the treatment room, an actor's T-mark is visible on the floor below the gurney.
Visible crew/equipment: When the guys are on the tower ride during the rescue, the shadow of the chopper (and its rotating rotor blades) doing the aerial filming becomes visible, when the ride reaches the bottom. Then the shadow of the entire chopper moves in directly in front of the ambulance, as they load the ambulance.
Visible crew/equipment: At the station, when Johnny and Roy talk about The Stewardess and then while Chet is mopping the floor, the bulging outline of the mic transmitter is visible on the front, left side of Roy's shirt, above his belt.
An Ounce of Prevention - S6-E13
Visible crew/equipment: After the rescues at the ferris wheel, when Dixie walks in while Brackett is examining the patient, the actor's black tape mark is visible on the floor, just as Morton and the nurse switch places.
Visible crew/equipment: After Roy is electrocuted and falls from the second floor window, when Karen runs over to him and starts CPR, the bulging outline of the mic transmitter is visible on the back of Karen's white uniform.
Visible crew/equipment: After Karen, the new trainee, goes to the waiting room to speak to the elderly patient's wife, when Dixie walks over to Roy and Johnny to ask how she's doing, the outlines of the mic transmitter and wire are visible on the back of Dixie's white uniform.
Visible crew/equipment: In the ambulance, when Roy administers the bicarb and then the isoproterenol IV, the outline of the mic transmitter is visible on the left side of the third paramedic's shirt, as he's doing chest compressions.
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 ★