Now, Jor-El challenges credulity by claiming our planet is being drawn into the sun's orbit.

8 seconds sound clip from Superman (1948) - Superman Comes To Earth (Chapter 1).

You can hear this line at 00:06:28.392 in the Blu-ray version of the episode.

Quote context

[...]

(Volcano eruption)

- Here that, gentlemen? That is your answer.

- What manner of wizardry is this?

- Are you perpetrating a new horror for some base and personal reason?

- Krypton has experienced quakes in the past and has survived.

- Now, Jor-El challenges credulity by claiming our planet is being drawn into the sun's orbit.

- The doom of Krypton. Escape through the air.

- Gentlemen, are these not the utterances of a man whose mind perhaps has begun to wander?

- I, for one, refuse to be intimidated.

- This is my final plea. Time is our mortal enemy. We must prepare to escape in spaceships without delay. There is no alternative if our advanced civilization is to endure.

[...]