Factual error: When Suzanna and Lisa are at Daisy's house, Daisy lays out money for Lisa so that she can get pancakes, and the bill she laid down is one of the new bills. This movie is set in the 60s so of course they wouldn't have the new bills, considering they didn't start making them until 1998.
Factual error: The movie is set in 1967-1968 (69?). The Doors song, "Roadhouse Blues" was not released until 1970, on the album "Morrison Hotel". The song, however, plays at the party the two girls (Winona Ryder and Angelina Jolie) go to, when they "escape" from the hospital.
Factual error: Susanna dialed "O" and said, "Yes. I need an ambulance." A few seconds later, she said, "Daisy Randone. I think she killed herself" and then gave her address "23 Vicar Street." In that time period (1967-68), the Operator typically would have first asked what city and then connected the caller to the appropriate ambulance company OR the caller had to directly dial an ambulance. The city, phone number, and directions to the caller's house would have been requested. (01:33:10)
Answer: I think it does play a part. She prefers the fantasy worlds to real life. Look when real life happens, or they hear about something... She looks so distraught and unable to really cope. Telling lies lets her create her own reality that she CAN deal with and be happy in with a sense of control.