Appropriately, Number 1 is from Prescription: Murder, when Columbo seeks Fleming's professional advice. The same scene includes the great moment where Columbo admits he could listen to someone talk about him for hours.

#3 and #4 are from "Swan Song" and "Playback." Good job at beating me to the first two.

Spot on! I'm up against it here, trying to catch you three out. No. 4 is on it's way! I'm going to have to make them harder!

Geez! The only one I was positive about was Prescription: Murder. They're tough.

"Spot On"!!!! Another UK expression!!! I Love it!!! And I actually know what it means!! (....after I had it explained to me, that is... )

And David, we have to act fast when you are around.