NFL football (6:30 p.m., ESPN): Redskins at Cowboys
How I Met Your Mother (7 p.m., Ch. 2): Ted tries to make amends.
Dancing With the Stars (7 p.m., Ch. 4): The competition continues.
The Sing-Off (7 p.m., Ch. 5): The competition continues.
Terra Nova (7 p.m., Ch. 13): The Shannon family travels back in time.
Castle (9 p.m., Ch. 4): Castle suspects a costume-clad vigilante is responsible for the murder of an ex-con.