Other mistake: At The Boat explosion incident, when Roy and Johnny climb aboard The Boat Johnny says, "We'll set up the Biophone here," but subtitles read "We'll set up the platform here." Subtitles from Universal Studios 2010 DVD.
Other mistake: After Roy and Johnny get back to the station, when Johnny takes the container of milk out of the fridge, we can see the black tape around it covering the brand name. There's another container in the fridge with red tape covering its brand name as well.
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 ★