Continuity mistake: When Bridget, Daniel and the other guy are in the lift at the start, Bridget is in the centre of the lift. The other guy gets out and Mr. Fitzherbert replaces him. Then Daniel gropes Bridgets bum and we see them all get out - Bridget is suddenly in the corner, but the whole time she never moved. (00:15:00)
Continuity mistake: Towards the end when Mark Darcy finds her diary, you clearly see the number 29 as he pulls it from under the magazines, then when you see the diary it's open on pages 10 and 11.
Continuity mistake: After Bridget sprays the contents of the blender all over herself, there's a splodge on her right cheek - it changes shape when she answers the door. (01:01:10 - 01:02:00)
Continuity mistake: At the Darcy's party, near the end of the movie, Bridget's hair changes constantly: smooth to slightly mussed, barrette visible then covered with hair, and the location of her part shifting a bit.
Continuity mistake: There are two types of string used in the blue soup scene - plasticky type that florists sometimes use for the blue stuff, then ordinary string for when the dye has come out.
Continuity mistake: During the fight between Mark Darcy and Daniel Cleaver, when Daniel pushes Mark through the restaurant window, the text on the window changes in font, colour, and content. The first window features burgundy text when close up on the restaurant before and while the two go through it. However, the second window text is cream coloured and shown in wide shots with the restaurant in the background and after Mark and Daniel have broken it.
Continuity mistake: While Bridget and Daniel are driving to their "full-blown mini-break holiday weekend", Bridget lifts the sunglasses over her forehead with her left hand and holds the scarf at her neck with her right hand, but in the next shot before her scarf blows off her hands are in the opposite positions. (00:31:10)
Continuity mistake: When Cleaver is knocked-out on the floor, the amount of shattered glass around his head increases between the close-up and wide angle.
Continuity mistake: During the car ride scene with the scarf flying, the suitcase behind Bridget changes positions between shots. Before the scarf flies it's on the right side, but after the scarf flies it has moved to the center of the seat.
Continuity mistake: When Mark returns from the States, as he begins to kiss Bridget for the first time, from the camera shot behind him, his head is angled to the right. From the shot behind Bridget, it is angled to the left.
Continuity mistake: When Bridget has been invited to the dinner party (the one with all the couples) she has a drink - to start with it is two thirds full, next shot half full - she hasn't drunk any because she is talking next scene and it's two thirds full again.
Continuity mistake: After Bridget and Daniel Cleaver go out for a meal, they hail a cab outside the restaurant. The road is Shad Thames and is locked by gates at every exit every night and pedestrianised, so a) How did they hail a cab from a locked road? and b) Where could it take them to?
Continuity mistake: When Bridget writes her diary on 1st January, we see the fridge in the background at floor level, alongside other kitchen units. But later, just after Daniel has announced his engagement to Lara, Bridget opens the fridge to "eat the entire contents" - the fridge is now on the sideboard, with no units beside it, also its decorations are different. Later when Bridget is cooking, she opens the fridge and looks in - she is crouching in front of it, as if it is at floor level again. (00:07:36)
Continuity mistake: When her mother comes back home, the camera switches between a view of her Mum where you can see the back of her Dad's head, and the reverse shot. When she's saying "you must pay more attention to me", after she says "me" her mouth is open when you see the back of her head, but after it switches and we see her from the front, her mouth's shut.
Answer: Lots of times in book-to-movie situations and even in some remakes, the producers/writers/directors change names or events. It can be because of personal issues, legal ones or it can even be spur of the moment. it can also be unintentional,when they change it without the specific INTENTION to change it. I think in this case it was more likely that the character/or their name didn't have too much of an impact on the story line, so they didn't feel a pressing need to keep it the same.