Sam and Al from Catch a Falling Star:
"More misadventures?" "Adventures, old friend."

Sam from Genesis:
"As nightmares go, this one is taking a turn for the better."

Sam from The Leap Back:
"Gimme what I want, baby."

Ziggy from The Leap Back:
"Good night, Doctor."

Sam from A Leap for Lisa:
"I've got to get history back on track."

Ziggy from The Leap Back:
"It's about time you got around to me Dr. Beckett."

Al from 8 1/2 Months:
"It's impossible Sam."

Al from ???:
"Ain't it a kick in the butt?"

Ziggy from The Leap Back:
"He'll kiss the girls and make them cry."

The leap effect.

Ziggy from The Leap Back:
"With a million gigabyte capacity I'm quite capable of rubbing my tummy, patting my head, and doing a trillion floating point operations at once."

Sam from The Leap Back:
"Revenge is mine, thus sayeth the hologram."

Sam from A Portrait for Troian:
"At last, something sexual he's not into."

Al from 8 1/2 Months:
"Something tells me we're in big trouble here."

Al from It's a Wonderful Leap:
"Driver, take us to Bellevue and step on it!"

Part of the Quantum Leap theme.

Another part of the Quantum Leap theme.

Sam from Killin' Time:
"Welcome to my world."