In the scene at the beginning of the "illegal" match, when Ty and Al pull up in Al's car, you can see the boom mic visible as a reflection in the car door after Ty shuts the door (and slams his fingers in it).
When Maggie and Danny are in bed, Tony jumps up to look in the window. Each time he jumps he gets no higher than the bottom part of the window. When they show him standing outside, he is actually taller than the bottom part of the window.
During Lou's speech after breaking up Noonan's fight, the dartboard against the back wall in the caddies' shack switches from a regular darts to whatever game is on the back. The position of the dartboard also moves.
When Tony D'Annunzio and Danny Noonan are arguing about the price of a coke, Tony's hair is obviously being blown by an unseen fan to his left - in the camera angle shot from behind Tony. In the shot from Danny's perspective - Tony's hair does not move.
The lifeguard's tower is shoved into the pool. It can be seen floating in the pool in the scenes that follow, but the lifeguard himself is nowhere to be seen (and given his attitude in the previous scenes, he would likely be pretty irate with the caddies over this).
At the end of the scene where Carl is making the clay animal explosives, he is holding a fire extinguisher in his left hand and nothing in his right. In the very last shot he is holding a clay animal explosive in both hands.
When Judge Smails asks Danny "Are you my pal?" in his office, he's holding his hands together at his waist. The next shot, over his shoulder, he has his arms crossed at his chest, and a second later when the shot switches back to Danny's POV, they are back to his waist.
When Cervik comes into the club and gets into the argument with Judge Smails and Smails tries to choke him, Smails is wearing one tie, but when they retreat to the judge's office to discuss it like adults, according to Tye Webb, and Cervik challenges the judge to play golf for money, the judge is wearing a different tie.
When Ty is getting in some night practice he is seen struggling to line up a shot under a tree and in some shrubs. He finally takes a swing but no golf ball comes out. In the next split second scene the golf ball is going through the window at Carl's shack.
When Judge Smails is hit in the groin with the golf ball, the up close shot shows direct sunlight on his pants, when he looks back at Al Czervik the shadow indicates that he would have had to have been hit in the butt for shadow to show sun on his pants.
When Lacy is at Ty's home, he is preparing the bottled water. When he is walking to her he has the bottle in his left hand and the glass in his right. In the next shot when he is handing her the glass, the glass is now in he left hand and the bottle in the right.
Just after Ty douses Lacy with oil while giving her a massage, she exclaims "you're crazy (see trivia)," lifts her head and turns it toward Ty, totally surprised yet she is then immediately shown wither head down, facing away from Ty.
When Spaulding is stealing drinks at the fancy dinner and accidentally drinks a drink with a cigarette butt in it, his bow tie is clipped to his left shirt collar. Immediately afterward, when he stumbles out the front door of the club, the bow tie is clipped on his right collar.
According to the referee at the beginning of the final match, the format was to be team match play. In match play, the person who scores the lowest on an individual hole, his or her team is awarded the hole. The winner will have won more holes by the time 18 holes has been played, or sooner; i.e. one team being up by four holes with only three holes remaining to be played. On the last shot of the match, in which Ty says to Danny, "It's no big deal. If you miss it, we lose." However, this couldn't have been the case. Since they were playing the final hole, assuming it was the 18th, that means that the match was either all square (tied) or one team had a one hole lead with one hole left to play. If Ty and Danny had been ahead by one hole and Danny had missed the putt, Judge Smails and the Doctor would have won the hole with a birdie and the match would have been tied again, leading to a playoff. So if Danny did wind up missing the putt, they wouldn't have lost right there. If the match were tied going into the 18th hole, we can assume that because Danny was still putting after the Judge presumably made a birdie or a par, that means that Danny and Ty still had a chance to win the match. If there was absolutely no chance of them winning, the match would have ended. So with that made putt on 18, Danny would have either been shooting to match Smails and the Doctor's score, or to win. If the final putt was to match their score would have resulted in a tie and a playoff. If that putt was indeed to win, then Danny and Ty wouldn't have lost if he missed as Ty had said. Finally, if Smails and the Doctor had been up one hole with one to be played, surely the final putt would have put the pressure on Danny. We can assume because of the celebration after the ball finally goes in the hole, that Danny had at the very least won the hole. Even if Danny had made eagle and the Judge a par, it still would have only been a single point to team Ty and Danny. Therefore the match would have gone to a playoff with the match all square. Bottomline, there was no guarantee of a loss if he missed, no guarantee of a victory if he made it, or both.
At the beginning of the boating scene when Al takes over for his captain, he uses both hands to accelerate the two throttles of both engines of the twin-screw boat. At the end or the scene when he shuts down the engines, he only operates the lever for the port engine leaving the starboard one at full throttle. His boat would not have stopped.
In the closing cast credits, Sarah Holcomb was cast as "Tony D'Annunzio" when, in actuality, it was Scott Colomby who played the part. Sarah played "Maggie O'Hooligan". (This was fixed in later releases of the film.)
When Ty doubles the amount of the bet in the bar scene, he doubles it to 40,000 and tells Judge Smalls that his dad never liked him. Later on, Al and Ty double the amount of the bet again, to 40,000 apiece (from the previous 40,000 per team). This confused at least one viewer.
During the scene when there is a party at the club, Carl is hunting the gopher with his gun outside. He is moving from tree to tree, and you can see in the background that it is the daytime when it's supposed to be night.