The weapon Nobu uses in his fight with Daredevil is a Kyoketsu-shoge, a ninja weapon consisting of a double-edged blade with another curved blade attached to it. The blades are attached to a long chain that ends with a metal ring.
During his fight with Daredevil, Nobu wears the traditional red ninja garb of The Hand. In the Marvel comics The Hand is an ancient ninja clan and criminal organization, and become one of Daredevil's main adversaries. The war that Stick mentions in episode 7, Stick (2015), is actually a conflict between his band of ninjas, The Chaste, and The Hand. One prominent member of The Hand is Elektra, a character that is referenced to on several occasions during the season. The war between the Chaste and the Hand was previously used as the main plot in the Elektra (2005) live-action film.
The snake symbol on the heroin packets is the same as the tattoo on the chest of Steel Serpent, a major bad guy in the Iron Fist comic series.
When Matt breaks into the gym a fight poster can be seen for a match featuring Carl "The Crusher" Creel. Carl Creel is the Marvel super villain Absorbing Man.
Wesley mentions that a Senator Cherryh wants to meet Fisk. In the comics, Fisk backed a politician named Cherryh (apparently named after the s.f. writer C.J. Cherryh, who added the final 'h' at her editor's suggestion to make her name seem less like that of a romance writer).