1. Early in the film Lucifer makes Cinderella put the dog outside.
2. Note that double door in the kitchen, here's a shot of Lucifer look out of it.
3. The bells start ringing for Cinderella to get the women their tea.
4. She comes inside through the door she exited, which is that double decker door.
5. In one single take Cinderella pours the tea, puts it on a plate, and walks it to her sisters, continuously....
6. Now where does the dog enter the house at the end?
Oh that's right, through that double door. Seeing as how Cinderella was clearly on the most direct path up the stairs, which clearly goes through the meeting room and up that staircase that she descends at the very end, it is logically sound to reason she took the most direct path to reach the women, which also happens to bypass that door that leads to her tower. Now unless the film does not show us another staircase, and even then we would have to believe that the dog is in no major hurry to get to Cinderella, which is clearly not the case, he would have to run straight through the meeting room to get up the stairs. I do not care how absorbed they all are in the slipper thing, there is no way that not one of them is unable to see a large dog running through a room, up a staircase, and then breaking down a door that leads up to Cinderella's tower. Jesus, just because you do not have a problem with the scene does not mean that the scene is not inherently flawed.