Charles Jarman, the actor who played the unnamed henchman The Joker killed, mentioned that director Christopher Nolan told him they were going to do a couple shots where Jarman had to quickly sneak the pencil away as he was going down, which proved difficult to do since the pencil was stuck to the table.
So instead, The Dark Knight took the practical route with the pencil trick, resulting in approximately 22 takes across two days and using two kinds of tables: a regular one and one made of galvanized rubber.