Revealing mistake: At World Picture Corp, when John and the guy with the broken clavicle are lowered from the overhead joists they're both wearing lifebelts buckled around their waists. The problem is that once they reach the ground, we can see the additional carabiner attached to John's lifebelt, which is also attached to extra green support protruding from under John's shirt. We can also see the victim's additional carabiner going under his flannel shirt. While Roy is on the line with Rampart, when John removes the victim's lifebelt, the extra carabiner is still protruding from under the victim's shirt and John places his hand over it. (00:27:00)
Visible crew/equipment: After spending all night on the job, when the tired guys of 51 are at the basketball game, the outlines of the mic transmitters and wires are visible on the backs and sides of 51's jerseys, particularly when Roy gets injured. (00:36:00)
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 ★