* In episode 24 when Light regain his memory after snatching death note from L's hands he speaks by the same voice as The Unnamed Shinigami and says: "I've won. just as planned!" especially the part "just as planned!" is a total match.
* He walks with something of a limp, which could be due to the injuries Light sustained when he was shot several times by Matsuda.
* Ryuk himself has some vague dialogue that could be interpreted as him referring to the Unnamed Shinigami as Light: After looking at his own Death Note, Ryuk speaks to Light as if he were there; "You were not God. You were just...gone already?" This could mean Ryuk was addressing the unnamed Shinigami as Light or that he was simply reminiscing.
* The shinigami doesn't stay to hear the end of the story, which could imply he already knows how it ends.
* Ryuk has also been knowned for not telling the truth, for example when Misa told Light how to kill a Shinigami Light looks at Ryuk with a face saying “why didn’t you tell me?” Ryuk says something like “you didn’t ask”. So he doesn’t tell Light about everything. And if he would’ve told Light that he would become a Shinigami after death Light would probably kill himself as that would mean he would become a Death God
* Ryuk also tells Light before dying that he will probably like the “other side”.
*He has bright red eyes, like Light's red eyes at certain points in the anime
*Light also stands in the Shinigami Realm during the end of the second intro sequence - a possible foreshadowing of his reincarnation.