The Giants missed out on a place in the semi-finals on Friday night as they were beaten 16-18 at the John Smith's Stadium.
"I am massively disappointed about the season. We started round one with big expectation but consistency throughout the year cost us. It wasn't just week by week but within games," Anderson told Sky Sports News.
"We have had inconsistencies within performance and individual performances throughout games. It ends up hurting you. We went into this game with every expectation of winning, going to St Helens and winning the competition - but it has gone."
Catalans will visit St Helens in the first playoff semi-final on October 2 before Warrington Wolves travel to Wigan Warriors the following day.