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).

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.

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.

The newspaper that contains the words 'Doubt Fire' was the same newspaper used on the first episode of Charmed.

At the very end of the film, the Hillard's are interviewing a very stern woman. Her name is crossed off the list that Lydia is holding and we can see her name is Paula Du Pré. Paula Du Pré is the film's Associate Producer.

When the kids are at Robin Williams' flat for the first time, when the little girl says "We're his goddamn kids too" (mimicking Williams), this had to be shot numerous times as she couldn't keep a straight face. You can actually see her almost start laughing if you look close. Source - Commentary track on DVD.