Other mistake: When O'Neill first goes to visit Teal'c in his cell the symbol of Apophis on Teal'c's head is upside down.
Brief Candle - S1-E9
Other mistake: Jack made it quite clear that he was 40 years old when talking to Kynthia, so if his birthday was in '52, that would put him at 45, instead of 40 years old.
There But For the Grace of God - S1-E20
Other mistake: When attempting to dial out about 26 minutes into episode, the Earth gate point of origin symbol locks (indicating that all the symbols are finished encoding). But then "chevron 2 encoded" is announced.
Answer: While the series was undeniably successful, filming it is a long process, taking many months of often long days. Anderson, after several years of doing this, wished to spend more time with his young daughter, who he felt he was neglecting, and requested that his role in the series be scaled back. Ultimately, he decided to leave the main cast altogether and only make occasional guest appearances.
Tailkinker ★