The error: The date on which supporters are urged to caucus, Jan. 14, is 11 days after the caucuses. It appears to be an old card, printed well before the Iowa Democratic Party settled on the Jan. 3 date in late October.
In any case, it's an odd organizational glitch. Supporter cards are the central pieces of the candidates' Iowa operations, and candidates and their staffs are constantly urging Iowans to sign them, in the hope that this public pledge of support will guarantee that Democrats stick with their pledge in the public caucus situation.