Kelly pitches from a windup with a runner on base instead of the stretch which allows him to check the runner's lead. In a real game the runner would easily steal the next base at each occurrence of this type of windup let alone the double pump Kelly uses.
Vernon's jersey number is 22 for St. Louis, but in one scene and game, his jersey number is 26. His first jersey number, as he was trying to get the Saint Louis owners to accept him, as a pitcher was 12.
When Vernon first discovers that the baseball is repelled by wood, the second piece of wood is two inches from the edge of the counter so that the ball jumps over, but then without being touched it is six inches from the edge allowing the ball to go around the end of the wood as opposed to jumping over.
When King Kelly relieves the pitcher in his debut game, the scoreboard reads Chicago 6, St. Louis (Kelly's team) 7, top of the sixth inning, with no outs. After Kelly retires one batter, his team leaves the field and celebrates their victory as they change out of their uniforms in the locker room. Perhaps, the game was one that rain had postponed, the previous day, when Vernon was strongly wanting to become a baseball pitcher, without any rookie team practice. Or there was an off-screen decision, among the managers, that the game was shortened to six innings, because Saint Louis had a weak team, and could not go nine innings and win a majority of their games, until Vernon Simpson, aka King Kelly was tested and accepted.
In the final game scene, (just before the World Series), a left-handed batter wearing number 43 runs to first base. His chest was not visible, until he nears the base. Instead of wearing the St Louis jersey, the logo on his chest is that of the Chicago Cubs.
In the first baseball game sequence, they start outside the St. Louis stadium. The (stock) game footage they use immediately thereafter is obviously Chicago's Wrigley Field. The movie footage is then inside the stadium in St. Louis again.
When in the lab as the professor tries to hit the baseball hanging by the string, it's obvious that the string is being jerked up. If the ball moved up on its own, the string would go limp since it can only resist tension, not compression.
Kelly's pitch violates the laws of physics. Assuming arguendo that a chemical exists that avoids wood, when a ball with that substance on it approaches the plate and the batter swings, the ball would change its trajectory either up or down to avoid the wood and would then continue on that new path. It would never "jump over" a swinging bat, then go back to its original trajectory.
When Vernon asked his two students, (the hot-footer & the recipient) to meet him on the baseball field at 5:00 A. M. the next day, no where in the United States, is it lit, or even dawn, at 5:00 A. M. in the spring. Perhaps, Vernon's 5 o'clock remark, was referring to another time zone, like Pacific. When it is 5:00 A. M. Pacific, it is 7:00 A. M. Central Standard Time. (Apparently, the 5:00 Time, is/was World Time).
Kelly's pitch takes a "hop" only when a batter swings at a pitch. If the batter doesn't swing, its just a medium straight fast ball. Sooner or later somebody would notice that the pitches swerve only when swung at, and would start taking a look at the ball and discover that it had been doctored.
If the Professor's magical chemical really repelled wood, then when swinging the bat at the ball it would be pushed away from the batter and cause a foul or in field ball, rather than just hop over the bat.