Factual error: The author reveals her limited Spanish when she has a character, purportedly a native Spanish speaker, saying to Ingrid, "¿Cuál es su nombre? Su hija es más guapa." Which translates to, "Which is her name? Your daughter is more beautiful." But in the book, those words are rendered as, "What is her name? Your daughter is very pretty." Not only does the author a) mistranslate the Spanish, but she b) gives the woman words no native speaker of Spanish would say.
Continuity mistake: The timeline of the book's events, including before Astrid was born, is fuzzy if you try to put it together. According to her mother Ingrid's diaries, Ingrid met Klaus (Astrid's father) in 1972. The spring when Astrid is 13 1/2, the book talks about "riots down in L.A." which occurred only one time in L.A. since the 1960s: 1992, which would put Astrid's birth in November of 1978. That makes 6 years from when Ingrid met Klaus to when she had his baby, and she is notorious for having a short attention span with men: no way she would have stayed with any man for 6 years, even one she was in love with as much as she was with Klaus. (She even confirms this later when she describes a 2-or 3-year long relationship with her cellmate as "the longest relationship I've ever had" other than her own daughter). Also, when Astrid is 17, her mother writes to her "it's the millennium", which taken literally would mean Astrid was born in 1983. If you take Astrid's supposed birth date of 1978, it should be 1995 when she is 17 - five years before the millennium, and too far away for anyone to start saying that yet. Plus, Astrid moves to Germany when she is sometime between 18-21, which according to that 1978 birth date makes it 1996-1999, a full 6-9 years after unification, yet Astrid describes a Germany suddenly starting to sell the suitcases they'd held onto all during the days of East/West Germany - not plausible for this to still be so 6 years later. The gist is: there are several possible timelines for the book's events, but they do not match up when put together.