You could be more right than you know.

4 seconds sound clip from the Indiana Jones and the Last Crusade movie soundboard.

You can hear this line at 00:21:34 in the Blu-ray version of the movie.

Quote context

[...]

- But as you pointed out, it's incomplete.

- Now, the second marker is entombed with the knight's dead brother.

- Our project leader believes that tomb to be located within the city of Venice, Italy.

- As you can now see, Dr. Jones, we're about to complete a great quest that began almost 2,000 years ago.

- We're only one step away.

- That's usually when the ground falls out from underneath your feet.

- You could be more right than you know.

- Yes?

- We've hit a snag. Our project leader has vanished, along with all his research.

- We received a cable from his colleague, Dr. Schneider, who has no idea of his whereabouts or what's become of him.

- I want you to pick up the trail where he left off.

[...]