There's nothing wrong with the mirror. I look in it often. I sit here and look at these four walls. Then for a change, I look at them in the mirror.
10 seconds sound clip from the Dead of Night (1945) movie soundboard.
You can hear this line at 00:49:37.611 in the Blu-ray version of the movie.
Quote context
[...]
- But I won't stand it, not while I've strength to move at all.
- Darling, sit down and listen to me. You're not well.
- And a good thing for you and your precious lover that I'm not.
- If I could move out of this room and break him in pieces...
- Peter, it's the mirror. I've found out what's wrong with the mirror.
- Peter, I haven't even seen Guy. Anyhow, you know we've always treated him as a joke.
- Yes, I know we've always pretended to, but I knew what was going on all the time.
[...]

 Dead of Night (1945)
 Dead of Night (1945)  Phantom of the Opera (1943)
 Phantom of the Opera (1943)  Scooby-Doo, Where Are You! (1969)
 Scooby-Doo, Where Are You! (1969)  Halloween III: Season of the Witch (1982)
 Halloween III: Season of the Witch (1982)  Knight Rider (1982)
 Knight Rider (1982)