Corrected entry: It appears the director decided to add an airport scene where Jennifer Garner flies off from Los Angeles to San Francisco to see her "boyfriend", while the following scenes indicate she was still in her home town. First, Ashton Kutcher tries to stop her, telling her that the boyfriend is married and he delivered flowers to the wife himself. Then, after Jennifer finds out where the boyfriend will be dining, she poses as a waitress. As she leaves the restaurant, the maitre d' says, "My son loves being in your class". (Long drive to school from S.F. to L.A.). Then Garner drives off and goes, by car, to a party in L.A.
Corrected entry: When Ashton Kutcher attempts to stop Jennifer Garner from boarding the plane to San Fransisco, it appears as if he is unsuccessful since you see her board the plane. However, in the next scene she appears in, the receptionist at the hospital answers the phone "Los Angeles Hospital" and then Jennifer confirms she is in LA during a cell phone conversation what appears to be minutes later.
Correction: The movie never showed her boarding the plane, only walking away. As the entry states she confirms later that she is still in L.A. No mistake here.
Correction: Jennifer never went to San Francisco. You see her walk away towards going through the tunnel. However later you see her at the hospital where Harrison works. The receptionist picks up the phone stating "Los Angeles Hospital" just before the other nurse informs where Harrison will be having dinner with his wife. The next scene, Jennifer is walking while leaving a message to Jessica Biel that "she is still in L.A.". Then later she goes to the restaurant. "My son loves being in your class" is perfectly fine since Jennifer is in LA and not in SF.
But why would Jennifer go to the LA hospital to ask if Harrison is there when he said he would be in SF for the night?
Because he's having dinner with his wife.
I agree she probably decided to not board the plane and check out the drs marital status herself but they should have shown her not getting on the plane. Very confusing.