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 Czervik 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 Czervik 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 golf rule 16-2, When any part of the ball overhangs the lip of the hole, the player is allowed enough time to reach the hole without unreasonable delay and an additional ten seconds to determine whether the ball is at rest. If by then the ball has not fallen into the hole, it is deemed to be at rest. If the ball subsequently falls into the hole, the player is deemed to have holed out with his last stroke, and must add a penalty stroke to his score for the hole. Danny never reaches the hole due to the explosion and therefore rule 16-2 is not invoked. The match stands as is. Danny and Ty win.
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.)
While Danny making that last putt effectively tied the game, meaning neither team lost nor won, Al's last-second bet of "Double or nothing he makes it" essentially negates the original bet and creates a new one. Since Judge Smails agrees to this new wager before Danny makes the putt, Smails loses the final bet and has to pay up.
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.