Passages in John's Gospel about the Old Testament pointing to Christ:

The whole Bible points to Jesus Christ - the Old Testament, as well as the New Testament.

This is not just something that we are 'reading back' into the Old Testament in an unwarranted way. It is how the writers of the New Testament understood the relationship between Jesus and the Old Testament. It is also how Jesus himself understood it.

The following references show how this relationship is understood in John's Gospel:

In John chapter 1 verse 45, Philip tells Nathanael,

We have found the very person Moses and the prophets wrote about! His name is Jesus, the son of Joseph from Nazareth.

Both Philip and the writer of the Gospel understood Moses and the prophets to have been writing about Jesus.

In John chapter 2 verse 19, in the context of clearing the temple, Jesus tells the Jews,

Destroy this temple, and in three day I will raise it up.

The Jews are amazed, because it has already taken 46 years to build the (still incomplete) temple. However, Jesus is talking about his body. John goes on to say,

After he was raised from the dead, the disciples remembered that he had said this. And they believed both Jesus and the scriptures.

In John chapter 5 verse 39, Jesus tells the Jewish leaders,

You search the scriptures because you believe they give you eternal life. But the scriptures point to me!

And in verse 46 of the same chapter, he says,

...if you had believed Moses you would have believed me because he wrote about me.

Finally, in the context of the Peter and John discovering the empty tomb, Johnchapter 20 verse 9 says,

Until then they hadn't realized that the Scriptures said he would rise from the dead.

In his commentary on John's Gospel at 5:39-40, Don Carson says that

(The Gospel According to John, Pillar New Testament Commentary, by D. A. Carson, Eerdmans/Apollos 1991)