Goofs

When Fletcher goes to the bathroom to beat himself up, he is clearly wearing a different suit than in the courtroom.

Moments after Fletcher's watch reads 8:45, it indicates 6:45.

Right before he gets pulled over by the police, Fletcher passes the same maroon Ford Taurus twice.

When Audrey is about to put candles on Max's Birthday cake, she takes the candles out of the box and puts them on the counter. In the next shot they're in the cake.

During the courtroom scene, Fletcher drinks 5 glasses of water. But the amount of water in the pitcher stays the same.

Fletcher would not be trying both defendants (criminal code) and divorce cases (family code).

When Fletcher is brought back from the restroom and tells the judge a madman beat him up, the judge merely asks if he's alright to keep going. In reality, a lawyer being physically assaulted inside a courthouse is an extremely serious incident and would result in the trial being immediately put on hold, the police being contacted who would then put the courthouse on lock-down and would establish a perimeter around the surrounding area before embarking on a manhunt with K9 units and SWAT.

If Fletcher is an associate and not a partner at the law firm, he would not have a large fancy office or be trying cases on his own.

Fletcher is able to successfully argue that an underage marriage is valid because an underage prenuptial agreement is not. They would either both be valid or both be void by virtue of her age at the time. If she could not enter into a prenup at age 17, she could not enter into a marriage at that either either. Also, Samantha Cole admits on the stand to having lied about her age on her driver's license and marriage license. She cannot then ask the court to essentially reward her deception.

Samantha's husband's lawyer presents a tape recording to be used against Samantha in court. Tape recordings are not admissible as evidence in a court of law, even though the content of the tape is irrelevant in Mrs. Cole's case.

Airplanes don't serve beverages before takeoff; Only in Business Class and First Class.

When Fletcher is chasing the 747 down the runway, the plane is almost ready to take off. This means it is still taxiing to the end of the runway, giving Fletcher more than enough time to keep up with it and stop it. The call saying they are ready to take off comes right before Fletcher throws the shoe, which would've put it at that impossible speed.

When Kenneth Falk is called to the stand, he simply gets up and walks to the stand. However, if a witness is to be called to the stand, they must be called in from outside the courtroom, except in the case where the witness arrived prior to their being called. Falk did just that as, seeing he was introduced by Mrs. Cole in the previous scene, and they were going through what he should say, it's clear Falk did not actually sit in on any part of the other side's presentations.

When Fletcher encounters Miranda in the elevator, and flees through the stairwell, the false wall labeled "21st Floor Roof Access" visibly shakes as he bounces off it.

The toilet noticeably flexes when Fletcher smashes his head between it and the seat.

When Fletcher was pounding himself on the marble wall, the wall shakes revealing that the restroom was really a temporary film set.

When Jim Carrey is seen among the emergency response personnel at the airport dressed as a firefighter (a nod to Fire Marshal Bill), some of the extras cast as onlookers can be seen turning their heads towards him and then laughing.

The jugs used by Fletcher in the courtroom and by the flight attendant on the plane to Boston are the same, appearing overly matching.

Max's curse onto his father that he could not tell a lie for one day also meant that he could not hold the right answer in against his will as evidenced by his various antics in his office, when he could not call blue pen as red, because he knew it was a lie, and also about giving Fletcher's secretary a raise "out of his own salary," which made her quit. Fletcher demonstrated numerous times that he could not simply not answer a truthful question.

Fletcher's secretary recounts the apocryphal tale of a burglar falling through his victim's roof, injuring himself and successfully suing the homeowner. As of 1985, this is legally impossible in the state of California.

However, this tale seems inspired by the real case of Bodine v. Enterprise High School, from an incident that took place on March 1, 1982. A teen fell through one of the school's skylights while trespassing (allegedly during an attempted burglary), sustained grievous injuries, and was allowed to proceed with a suit against the school district. However, the claim was instead settled for a large amount by the district's insurance company. In October 1985, and partly as a result of this incident, Statute 847 of was added to the California Civil Code. It renders public and private property owners non-liable for injuries or deaths sustained by persons who achieve such in the course of or after committing a crime on that property.

When Fletcher gets his car towed and arrives at his wife's house in a taxi, he throws cash at the driver from the back seat. The sound does not match the throwing of the cash.

In court, during dialog between Fletcher and Samantha.

Fletcher wins the case because his client was too young to enter into a contract, namely a prenuptial agreement, but a marriage is also a contract she would be too young to enter, and thus the marriage should be annulled.

Just before Greta storms out of the firm, she asks Fletcher of the unfair ruling in favor a burglar who'd broken into her friend's house, "Is that justice?" After Fletcher's reply shocks her, he frantically tells her that he didn't understand the question. This is a lie since he clearly did understand it. The only possible way of explaining this is that Fletcher is so used to defending people he knows are guilty, he sides with the burglar in this case.

Fletcher literally cannot tell a lie. Yet while talking on the phone with Audrey about Max in school, he tells that he was "certain the case would settle" and it didn't so he had to be in court. This is a lie because although he tried to settle as a panicked last ditch effort to get out of trouble, he was never "certain" the case would settle.

The premise of the entire movie is actually flawed: it is Max Reede's wish that his father, Fletcher Reede, not tell a lie in 24 hours. This did not mean that Fletcher, when being forced to tell the truth, instantly had to blurt it out loud. He could have just kept his mouth shut or changed the subject various times, neither of which constitutes lying.

In real life, Judge Stevens would only have the power to issue a contempt ruling against Fletcher when the court is in session. When the court is adjourned, he would not.

Fletcher is unable to come up with an honest argument for a continuance. However, having been brought onto the case just a day or two before trial is a perfectly valid reason. His ignorance of the settlement offer is itself evidence that he needs more time to look at the case file.

Fletcher's only "honest" objection to an audio recording is that it is "devastating to his case." He fails to object on the grounds that California law requires the knowledge of at least one party that they are being recorded, which Mrs. Cole and her lover clearly did not.

When Greta asks Fletcher about her raise, Fletcher says "I didn't understand the question". He clearly understood the question all along; therefore he told a lie when he shouldn't have been able to do so. The only possible way of explaining this is that Fletcher is so used to defending people he knows are guilty, he sides with the burglar in this case.

When Fletcher asks Samantha what the year of birth reads on her birth certificate, Dana objects and asks, "What does this have to do with anything?", but Judge Stevens immediately replies, "Overruled. Mrs. Cole, answer the question." However, since this technicality has not yet been added to the evidence, in real life, if Judge Stevens had no idea where Fletcher was going with this argument, he would need to ask Fletcher to make a proffer (add evidence in support of his argument). He would not simply allow an unexpected argument with no supporting evidence to come in.