Dexter was 20 years old when he graduated high school. His driver's license indicates he was born in February of 1971. At the start of season 6 Dexter attended his "Class of '91" reunion.
Starting from this episode, Jamie is Harrison's babysitter but why Sonya is replaced with her isn't explained at all.
Travis Marshall asks the fruit vendor for oranges before killing him. Oranges are famously used as an omen of danger or death in The Godfather Saga.
During the crime scene at the fruit vendor's stand, the intestines on the scale show their weight to be a little less than 3 lbs. In an average adult, the small and large intestines together weigh 7.5 lbs. The small intestines weighing 3.5 lbs and the large weighing 4 lbs.
There is no Our Lady of the Gulf Preschool in Florida. The street signs are not real in the shot of the school. The actual preschool is the Belmont Heights United Methodist Church, in Long Beach, CA.