Other mistake: After the knife fight and the Captain giving Edmond the name Zatarra, the scene cuts to the ship entering a port and the words "three months later" are shown on the screen. By the movie timeline it should have said "Three Years Later." (01:05:20)
Continuity mistake: In the late scene where Edmund and Fernand are fighting, Edmund thrusts his sword through Fernand's right side. Later in the death scene, the sword is in Fernand's left side.
Visible crew/equipment: While Edmond is Fighting Fernand in the dining room there is a crew member that is in one of the mirrors for a second.
Character mistake: After Edmond changes his identity to become the Count of Monte Cristo, he is addressed several times as "Your Grace." "Your Grace" is a term of address used when addressing dukes and duchesses. He should have been addressed as "Your Excellency", which is the address given to counts and countesses.
Continuity mistake: Towards the end while Dantes fights Mondego the sun changes between shots.
Answer: I believe it's just because there is a dirty smelly man that she doesn't recognise visiting her ailing grandfather, she just wants to keep an eye on things.