At the 2nd game when Deborah calls the Manager to put Hinkley in the game, the announcer says it's the top of the 3rd inning. Just after the call, the two thugs kidnap Deborah and take her to a house. When Ralph and Maxwell arrive only a few minutes later, the radio that is on in the house says the game is going into the 9th inning. Not nearly enough time time had passed for the game to go from the 3rd to the 9th inning.
When the man sat at the bar is talking to Al the barman discussing Ralph's short lived career and trying to recall his surname, the man hasn't any spectacles but in the next shot he is seen wearing them.
When Ralph gets called out of the bullpen to pitch in the game, he puts on a dark blue jacket as he walks to the mound. In the very next shot of him arriving at the mound, the jacket has disappeared.
At the end when Ralph gets up to bat, he has a helmet on. After he hits the home run and is running the bases, he no longer has the helmet, but tips his hat to the crowd. Then, when he is running to home plate, he has the helmet on again.
After a Stars batter grounds out to end the inning (and setting up Ralph's pitching debut), the radio announcer says the game is going into the bottom of the ninth. The Stars are the home team in the game and would be the team hitting in the bottom of an inning.
Ralph comes up to bat in the bottom of the ninth, and when the pitcher throws the ball to him you can see his uniform number (#15) peeling off of his jersey showing that it is nothing more than an iron on, similar to what a little league baseball uniform has. Real MLB uniforms have the names and numbers embroidered on them.
When Ralph and Bill go to the house to rescue Debra the announcer on the radio says that it's in the 9th inning. But the clock shows the time is 2:10 PM. This would mean that the game had started at 11:00 A.M. , which would never be the case.
The door the hoods go through to the owner's suite in order to kidnap Debra Dante has a sign over it reading "Emergency Exit".
When Deborah calls down to ask the manager to put Ralph into his second game (just past 35:00) she walks too far to the left during the call and the seats are clearly empty.
When Markie Post tells Ralph about the Mike Douglas show he repeatedly says how excited he is that Mike Douglas called to have him on the show. But the dialogue is overdubbed and it was clearly filmed with Ralph saying "Merv Griffin" not Mike Douglas.
Around the 17 minute mark, a low-flying Ralph is chasing after the villain's car. The scene features the front view of William Katt flailing about, composited over footage taken from the rear of a moving vehicle. Intercut with this is live footage of Katt's flying stunt double, seen from the back, reaching out for the villains' sedan. While taking a corner, it's possible to see that the stunt double is actually leaning over the edge of a truck's tray in a diving position.
The championship series is supposed to be between a team from the eastern division and one from the western division. The "Oakland Mets" appear to also be from California which would not be an eastern team.