Visible crew/equipment: When Station 51 is dispatched to a vehicle accident in the canyon, en route there's a shot from the POV of 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.
Transition - S4-E15
Continuity mistake: After Gil and Johnny have lowered the man from the amusement park ride, Gil, who's wearing the backpack, rappels down first and reaches the ground. Then when Johnny hooks in and rappels down, there's a shot of what is supposed to be Johnny rappelling down, but it's actually a shot of Gil, because it was Gil who was wearing the backpack.
Continuity mistake: After Squad 51 gets back to the station, Roy and Johnny remain in the squad discussing Roy being the coach, and when the dispatcher drops the tones, we see a closeup of five pair of legs rushing out of the kitchen, even though we should only be seeing four pair of legs, since Roy and Johnny are already in the squad.
Revealing mistake: When Squad 51 gets back to the station, while Johnny's trying to convince Roy to coach their singing, the usually highly reflective chrome surface of the spotlights have been sprayed with a dulling spray, to temporarily dull the finish for this shot.
Camera Bug - S4-E10
Continuity mistake: After Roy and Johnny are dispatched to Station 68, Bob is lying on the floor with his shirt buttoned up and Roy has his hand on Bob's chest taking his respiration, but when it cuts to Bob's closeup his shirt is already unbuttoned, with the ECG electrode discs and leads in place on his chest. Additionally, in Bob's closeups the leads go from attached to the discs, to unattached, to attached again.
Revealing mistake: When Johnny and Roy are at the top of the open drawbridge, Johnny is wearing a watch on his left wrist, but when his stunt double rescues the woman in the car dangling off the edge, he is not wearing a watch. Additionally, the stuntman's pompier belt has a large axe sheath attached to it, but Johnny's life belt does not, and the stuntman's arms are much hairier, as usual.
Continuity mistake: When Johnny and Roy are with the boy who is in anaphylactic shock from the bee sting, Johnny's watch reads 2:25, then 2:35, and then 2:25 again.
Transition - S4-E15
Visible crew/equipment: At the start of the episode, when Captain Stanley leans over to hang up the telephone and walks out of his office, the outlines of the lavalier mic transmitter and wire are visible on the back, left side of his shirt.
Visible crew/equipment: When John and Roy help the driver out of the overturned armored truck, the bulging outline of the mic transmitter is visible on the left side of the driver's shirt, and when Roy's arm is around the man's waist, Roy even puts his palm over the mic transmitter as he bends to pickup the man's gun.
Character mistake: When Dr. Brackett talks to the attempted suicide's boyfriend, he tells Brackett that the girl has already attempted suicide a total of three times, and the first time she was hospitalized, but a minute later when Dr. Morton reads the hospital records and tells Brackett that the girl attempted suicide the previous year and was hospitalized, Brackett then tells Morton that her boyfriend said that she tried it three additional times. It was just a minute earlier that the boyfriend said two additional times, not three.
Camera Bug - S4-E10
Continuity mistake: When Johnny's leaning through the windshield of the truck carrying dynamite, using the jaws to free the driver, Marco's behind Johnny with the hose fogging them down, and Johnny's clothes get soaked, but in the closeup as Johnny pulls the driver from his seat, Johnny's shirt is completely dry.
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.
Visible crew/equipment: During the structure fire, after Roy and John climb out onto the ledge and the fire flashes in the exterior shots, the next interior shots we see shows stacked boxes falling as the fire flashes through the doors. The interior shots are from episode 3x7, "Promotion", during the structure fire, after the security guard is taken down the ladder. We can even see a crew member's hand pushing a lower box which causes them all to fall.
Continuity mistake: During the fire at the chemical plant, the distinctively marked SCBA tanks that Captain Stanley, Johnny and Roy are wearing, when they're searching for the missing man, change when they're inside and then finally exit. Note the different stickers, or lack of stickers, on their tanks.
Visible crew/equipment: After the fire at the Kiddytime Toy Factory, when Roy is in the ambulance and Johnny closes its back doors, the location set lighting is reflected on the glass of the ambulance doors.
Visible crew/equipment: When the dispatcher calls for Station 51 to respond to the "structure fire at the Kiddytime Toy Factory," while Captain Stanley is at the radio receiver base station, the reflection of the camera equipment is visible on the back of the squad's cab as it trucks left.
Continuity mistake: When the deaf woman is lying on the sidewalk having contractions, Johnny and Roy carry the pregnant woman on a cot into the market, and in the closeup of her face she is still lying on the sidewalk outside.
Smoke Eater - S4-E16
Continuity mistake: When Captain Robertson voices his disapproval about the paramedics, while the guys are in the kitchen eating, there are plates, cups, saucers, and utensils on the table. Then Station 51 is called to respond to a child trapped at the storm drain, and when the guys run out of the kitchen we see behind them that the table is now bare.
Visible crew/equipment: At the scene of the swaying sign accident, when Roy and Johnny get the gear out of the squad the outlines of the mic transmitters are visible on the left side of Johnny's shirt and right side of Roy's. Once they're on the roof both of the mic transmitters' outlines are on the right sides of their shirts, and later when Roy and Gil are pulled up onto the roof, the bulging outline is visible again at Roy's right side.
Smoke Eater - S4-E16
Continuity mistake: After Dr. Early is called a miracle worker and then again tries unsuccessfully to get the apple from the machine, it cuts to Squad 51 pulling backwards into the apparatus bay, and the engine we see parked in the bay is the Crown from the first two seasons, not their current Ward LaFrance.
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 ★