Corrected entry: In the first series, Joey's sister Bessie has a baby boy, (Alexander) with an African American, Bodie. Here the baby is appropriately darker skinned. In the finale, as Dawson and Joey are reminiscing on the bench, both their siblings are playing and climb up the ladder and Alexander is Caucasian. Plus Dawson's mum didn't have her baby until a much later season, but here they are look the same age.
Corrected entry: In the earlier episodes you see the school sign many times which shows, Capeside, Home of the Wildcats. In Season 3, as Mitch takes over as head football coach, the school mascot is the Minutemen.
Correction: During the entire season 2, the school sign doesn't appear to have the "Home of the Wildcats" anymore. Also, there is a small insignia at the bottom - a blue tri-corner hat, representative of what Minutemen would wear. They must have made the switch during season 2.
Correction: Alexander is definitely not caucasian in the final episode. His skin is much darker than Lilly's and his hair is dark and curly. As for the age, Alexander might look younger than he is and Lilly older than she is. Alexander does appear to be older though.