Jenny has dyed pink hair until she uses the cleanser for the first time, then it is restored to it's natural blond color. However, there is no explanation why her hair is dark brown when she is in the ward.
When Jenny is reunited with her family, she points out that they had to return Silverthorn to his time (the year 2500) first. Petey says, "Wow, you've been to the 21st century? What's it like?" Petey only has to wait ten more years to find out. The 21st century began in 2000. Jenny visited the 26th century.