Continuity mistake: When Roy's shaving while Johnny's in the shower, Roy fills a bowl with cold water and tosses it into Johnny's shower stall, then goes back to shaving, and the shaving foam on Roy's face changes between these shots.
Visible crew/equipment: When Chet is trying unsuccessfully to get Henry to use the dog house, the outline of the mic transmitter is visible on Chet's back.
Revealing mistake: At the gas station, when the pump sparks and catches fire, we can see that it's not gasoline on the ground with the water from the fire hose, but instead it's floating thick gobs of stunt fire gel with burning flames.
An Ounce of Prevention - S6-E13
Continuity mistake: During the rescue up on the ferris wheel, Johnny's uniform shoes have changed into shoes with flat soles.
An Ounce of Prevention - S6-E13
Visible crew/equipment: When Station 51 is dispatched to the man who's ill on the ferris wheel, just as Engine 51 rolls out of the apparatus bay, in the closeup we see the reflection of the array lighting and the reflector screen on the side of the engine.
Visible crew/equipment: When Charlie stops at the station to service Engine 51, while Roy and John are trying to service the squad, the multiple reflections of location array lighting are visible on Charlie's squad, and on Squad 51's spotlight.
Family Ties - S6-E16
Visible crew/equipment: At the house fire, when Chet finds the teenagers in the attic, just after Marco climbs in through the window, we can see the moving shadow of filming equipment (looks like the boom) by the stool.
Visible crew/equipment: When 51's guys are at their practice game, the gymnast is injured and the outline of the mic transmitter is visible on the back of Johnny's T-shirt. (00:16:40)
Continuity mistake: At start of episode, when Captain Stanley walks in announcing the upcoming game against 16, the paper he's holding changes hands between shots. Then after Cap sits down, the paper again changes hands between shots. Also notice that after Chet finds Henry's bone behind him in the couch, he gives it to Henry then puts it back behind him again, then gives it to Henry once again.
Continuity mistake: When Captain Stanley is writing on the board about the practice game at 9:00 am on Thursday, the board was clean before he started writing, then the board is dirty, and by the time he walks away the board is clean around what Cap just wrote, and his handwriting and its position on the board have changed as well.
Continuity mistake: After winning the semi-finals basketball game, when Chet walks into the kitchen Roy places a glass of milk on the table in front of Chet, which vanishes in Chet's closeups.
Continuity mistake: During the basketball game against 16, after the ref tell John that he can't call timeout unless they have the ball, Marco passes to Mike, who passes it to Johnny. When 16 gets the ball the blonde player with blue wristbands shoots, but in the closeup it's a brunette without wristbands who scores the basket. Plus the fact that in the closeup the basket he scores in is the one on the other side of the court, and the next few closeups of 16 scoring baskets are in the opposing team's basket, on the other side of the court.
Continuity mistake: After Roy injures his ankle, when Captain Stanley tells Chet that he's replacing Roy, John squirts Cap with the water bottle soaking the front of his shorts, but when they get up to resume The Game Captain Stanley's shorts are completely dry.
Visible crew/equipment: After Chet gives Johnny the idea about the TV show, when Chet stands up to leave the kitchen the top of the set is visible at the right corner.
Visible crew/equipment: When Roy walks into the ER with the actor who plays Dr. Ned, the nurse rushes over to Roy, and when she asks him about the actor, we can see the bulge of the lavalier mic transmitter at the back of her uniform.
Visible crew/equipment: When Johnny and Roy are with the man whose fingers are caught in the chain of the garage door opener, just as the man's wife sticks her head out the door to direct 86 to the garage, the outline of the mic transmitter is visible on the back of her blouse.
Continuity mistake: When all the guys enter the apartment with the doctor lying on the couch, John's carrying the Biophone with his right hand and starts to place it down, but then it cuts to another angle and John's holding the Biophone in his left hand as he places it down.
Visible crew/equipment: At the studio, before John tests Wally's equipment, when Roy says that he's going to get their equipment from the squad, Johnny rushes after him and we see the reflection of the camera crane and array lighting facing Squad 51.
Visible crew/equipment: After Dr. Early tells Mr. Jefferson that he knows who he is, it cuts to Johnny at the table with the typewriter, and the shiny chrome surface of the coffee pot reflects multiple set lights.
Continuity mistake: At the scene of the vehicle accident, once Vince wraps the gauze around the head of the driver of the pickup truck, the same bystanders are standing in two places at once - on the sidewalk beside Engine 51 and across the street beside Squad 51.
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 ★