In the fourth Act when they are waiting for Kimble to come back to the apartment, Mrs. Decker is shown putting out her cigarette twice.
After the one-armed man tries to call Coogan from a pay phone to meet with him, when there is no answer the one-armed man hangs up and there is no sound for the coin return, and he just walks out of the booth.
After Mrs. Decker relapses and gets very drunk, Cogen comes by and asks her to remember to give a message to her husband before running off. A few seconds later when Kimble asks her about the message and struggles to get her to be coherent enough to tell him what it was. He then decides to leave and tells her to tell her husband where he is going. While it may be understandable why Cogen wasn't smart enough to leave a written message, it's inconceivable that Kimble didn't think to write a note to be sure Mr. Decker got his message. This would have even been good for the plot, since Gerard and the police Lt. would come by later anyway, and their discovery of Kimble's message would be a good dramatic plot turn.