Trivia: Adding to the 'carpe dentum' contribution, if you look at Pierce Brosnan when Mrs Doubtfire gets up from the table, he is moments away from bursting out laughing. According to the commentary track on the dvd, it was this reference to Dead Poets Society that tickled Brosnan but he managed to keep a straight face and so they didn't need to reshoot.
Trivia: In the scene when they are having dinner, and Mrs Doubtfire is fishing the teeth out of the wine glass, she says: "Carpe dentem - seize the teeth" This was a parody of "carpe diem - seize the day" from "Dead poets society". (Yes it's a well known Latin phrase, but the Robin Williams reference is the important bit).
Trivia: When Stu calls Daniel a loser at the swimming pool, Mrs. Doubtfire then picks up a lime and throws it at Stu, hitting him on the back of his head. Robin Williams managed to hit Pierce Brosnan on the third take and the lime you see was made of foam rubber. Mrs. Doubtfire then tells Stu it was a 'run-by fruiting' - this line was improvised by Williams.
Trivia: Near the end, when they are in court and Robin Williams makes his emotional closing statement, it actually had to be re-shot because the first time he did it, it was apparently just too much, and the crew were just left speechless. The director decided that this was perhaps a bit too much to take and so they re-shot it.
Trivia: Near the beginning, the kids are watching something on TV with a man transforming another man's face. This is the second episode of the 1963 television show The Outer Limits, known as The Hundred Days of the Dragon. Part of the plot of this episode involves a man wearing a mask and makeup pretending to be someone else. That's the plot of Mrs. Doubtfire as well.
Trivia: When Mrs Doubtfire accidentally sets herself on fire in the kitchen whilst preparing dinner for the family, the boiling water pot originally had a metal spoon in it. In one take, Robin Williams picked up the spoon and attempted to put out the fire with it, but the spoon was so hot that Williams ended up burning himself quite badly, so they re-shot the scene without a metal spoon and instead Mrs Doubtfire picked up a pot with potatoes in and dropped it on the kitchen floor.