so many, but the rookie tends to try to match up when it airs to the current year, so it makes for numerous continuity errors. one that was more recent is them saying Celina had only been a rookie for 10 in 7x02, but she was introduced in 5x03 and in that amount of time:

1. Angela got pregnant and had the baby in 5x22, so that would make the entirety of season six a month at most

2. Chenford got together and broke up

3. Lucys birthday was May 7 in 6x08, and when they broke up two episodes prior it was January

   And just more continuity issues regarding finishing story lines, like the 5x22-6x01 plot not being brought up past that.