Visible crew/equipment: While en route to the accident, just as we hear the dispatcher inform Engine 51 that the fire is out, in the exterior shot of Squad 51 there's black tape covering much of the lightbar's chrome atop the cab, which vanishes when they roll up on the accident scene.
Revealing mistake: When Roy's in the ambulance with the man who was rescued from under The Boat, he's on the Biophone with Rampart, and just after Roy says, "So we've occluded the arterial flow in the right arm," in the next shot from inside the ambulance, we can see that they pass a couple of parked GlamourTrams. The ambulance drives around Universal's lot while shooting the footage inside the moving ambulance, en route to Rampart.
Visible crew/equipment: When Roy and Chet find the unconscious boy in the camper, and Roy tends to the young boy, the outlines of the mic transmitter and wire are visible on the back, right side of Roy's shirt.
Visible crew/equipment: When Roy and Johnny are tending to the man with possible paralysis, who is lying on the ground, the bulging outlines of the lavalier mic transmitter and wire are visible on the back, left side of Johnny's shirt.
Visible crew/equipment: When Brackett walks into the adjoining treatment room to talk to Pete about his pregnant wife, and tells him to sit, the legs (wearing jeans) of the cameraman/crew member are reflected on the chrome of the gurney, as he walks forward when the camera dollies in for a closeup.
Visible crew/equipment: When Johnny, Roy, and the two ambulance attendants lay the injured pregnant woman onto the stretcher, two crew members' hands and a foot become visible as the camera pans too far to the right.
Visible crew/equipment: At the home of the pregnant woman who was shot, the only ones there with Dora are Pete, Roy, Johnny and Vince. When the two ambulance attendants bring in the stretcher, a crew member's entire right arm (wearing short, white sleeve with pinstripes) comes into view on the right side of the screen, as the camera pans back.
Continuity mistake: After Johnny and the attendants exit the ambulance with Dora, the pregnant woman, the ambulance is empty and the drug box is on the seat with the Biophone on the floor beside the seat, but in the next shot as the gurney is wheeled inside, the drug box is now on the floor between the Biophone and seat.
Continuity mistake: Before the fake eye test begins Captain Stanley hands each guy their own cheat sheet, and when Chet walks out of the day room upset about the eye test, John puts his cheat sheet into his shirt pocket just as they're being dispatched to the "accident and car fire." After the rescue, when John and Roy get back to the station John joins Chet by the lockers, and when John tries to prove that the eye test was a prank, John opens his locker and pulls out his cheat sheet, even though we saw him place it in his shirt pocket before the run.
Continuity mistake: When Squad 51 and the ambulance arrive at Rampart with the father and unconscious diabetic son, the type of ambulance that backs up to the ER entrance is a station wagon, but in the interior shot from Rampart the ambulance type is a truck.
Visible crew/equipment: When Johnny and Roy are at the home of the pregnant woman who was shot, the bulging outline of the mic transmitter is visible on the back, left side of Johnny's shirt.
Continuity mistake: When Dixie goes to the waiting room to get Pete Barlowe so she can bring him to see Brackett, we see Carol, the nurse with black hair, working behind the admitting desk, but in the next shot Carol is in the treatment room with Brackett and Pete's wife.
Revealing mistake: When John is in the moving ambulance with the pregnant gunshot victim, Brackett asks him if he hears fetal heart tones, and when John removes the stethoscope from his ears he leans back and we can see out the window that the ambulance is quite stationery, despite the siren.
Visible crew/equipment: After Chet's disappearing half-dollar trick, when Squad 51 is dispatched to the gunshot wound, as Roy and Johnny get into the squad numerous set lights are reflected on the squad's chrome spotlight.
Continuity mistake: When John and Roy walk into the house with the pregnant gunshot victim, only John's wearing a helmet and he places it on the floor near the victim's husband, but in all of John's closeups (from the unusual POV looking up at him) his helmet is on the counter. Additionally, there are blue glasses upside-down on the side of the dish drainer, but in those closeups of John the glasses have vanished, and the glasses vanish again when Roy helps the husband get on his feet. Also notice that there's now a blue glass in the sink.
Visible crew/equipment: In the locker room, after Chet tells Johnny that he knew all about the practical joke, when they walk to the door together there's a quick glimpse of the cameraman's reflection on the door's glass, before John tells Chet about the fictitious five dollar bill down by Mike's locker.
Continuity mistake: There are only two ambulance attendants who take the pregnant gunshot victim to the vehicle, but en route we see two attendants in the front seat - driver and passenger, and a third attendant is in the back with John and the victim. Then when they reach Rampart, the attendant that was in the back with John has vanished and he's the one who opens the back door from the outside. As an aside, in the ambulance, when John talks to Rampart about fetal heart tones, we see the attendant is actually mucking around with the IV drip.
Visible crew/equipment: When Roy and John get back to the station, and Marco walks up to the squad to talk to the guys about the practical joke they're going to play on Chet, on the squad's spotlight we can see the reflection of the camera, which is in front of the map.
Visible crew/equipment: When Station 51 is dispatched to a man trapped at World Picture Studios, just after they pass the studio's gate, in the moving shot from the left side of Squad 51, the reflection of the cameraman is visible on the lightbar atop the squad's roof.
Visible crew/equipment: After the fake eye exam 51's guys are sitting around the kitchen table, and when Chet tells them that he was sitting in the front row at the movies, there are moving shadows at the bottom, right corner of the screen, which do not belong to the guys.
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 ★