Other mistake: When Bella meets Edward's family, Esme's (Edward's mother) upper forehead (near her hairline) has no makeup, but the bottom portion does. You can see the difference between her pale vampire makeup and her natural skin (which is also shiny).
Other mistake: Bella's nasal canula in the hospital scene were all over her face in almost every shot and they were not connected to anything. (01:38:45)
Other mistake: When Bella is in the ER, the x-ray behind Dr. Cullen is upside down.
Answer: Alice can see the future (She can not read minds, thoughts and intentions). She has foreseen that Bella will become a vampire and Edward does not want her to tell Bella that.
Jazaray