Character mistake: When Dana Appleton objects to Fletcher badgering Kenneth Falk, the judge overrules because Falk is Fletcher's witness. You still aren't allowed to badger your own witness in a trial, which the judge should certainly know.
Liar Liar (1997)
1 character mistake
Directed by: Tom Shadyac
Starring: Jim Carrey, Cary Elwes, Jennifer Tilly, Maura Tierney, Amanda Donohoe, Anne Haney, Justin Cooper
Revealing mistake: When Fletcher is beating himself up he goes into a stall and squishes his head with a toilet seat. You can see that the white part underneath is made out of foam because it keeps squashing down.
Cop: Do you know why I pulled you over?
Fletcher Reede: It depends on how long you were following me!
Cop: Why don't we just start from the top?
Fletcher Reede: Here it goes. I sped, I followed too closely, I ran a stop sign, I almost hit a Chevy, I sped some more, I failed to yield at a crosswalk, I changed lanes at an intersection, I changed lanes without signaling while running a red light and SPEEDING!
Cop: Is that all?
Fletcher Reede: [Forced.] No. I have unpaid parking tickets.
Trivia: Jim Carrey turned down the role of Dr. Evil in Austin Powers so he could do this movie.





Answer: As you said, he was testing to see if the wish was broken--by going up to an attractive woman and talking to her. While we don't hear what happens, he apparently said something a little too "forward" to her (probably more forward than he would have done otherwise, hence the "not as well as I had hoped"), and got slapped, so he knew that he was still under the wish's effects.
Chanteuse66
But I want to know what he said to the woman.
It's deliberately made unclear what he specifically said, because him getting slapped in the face is the gag that shows the audience that he's still under the spell. If we heard what he said, then we would know right away the new wish wouldn't have worked. It's ultimately up to the viewer's imagination to decide what he told the woman.
Phaneron ★