Audio problem: After the sniper throws down the rifle, we see Captain Stanley start talking to Chet and Marco, though at first we don't hear anything, we then hear, "Put on your air masks, " but that is not Captain Stanley's voice we hear. Oddly enough, to me it sounds like John's voice. Have a listen.
Audio problem: When Roy and Johnny are with the sick dancer at the bar, Roy asks her if she's had anything to drink, and when we hear her say, "No, believe it or not, I don't drink at all, " her mouth says something else.
Smoke Eater - S4-E16
Audio problem: While Roy and John are with the asthmatic boy, Roy's on the Biophone with Rampart, and we hear Early say, "Administer 0.3 milligrams epinephrin IM," but his mouth is not in sync with the last part, and it looks like he actually said, "Epinephrin IV."
It's How You Play the Game - S4-E19
Audio problem: At the scene of the vehicle accident, Johnny asks the driver, "Where does it hurt?" but when he continues to ask, "Right here?" we can see he's not actually moving his mouth, just before he's punched in the nose by the driver.
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 ★