As you can see from the setlist image below, "Debra" was listed but with a note that Beck could/might call an audible and do something else. Apparently Beck started "Debra" but then declared he wanted to "let loose" and did "Minus" instead.
Out of basically nowhere, Beck ad-libbed a line from "Heartland Feeling" in the beginning of a notably epic "Where It's At."
[people and bands
Banjo: Gus Seyffert, Roger Joseph Manning Jr.
Bass: Justin Meldal-Johnsen
Clavinet: Roger Joseph Manning Jr.
Cowbell: Beck Hansen, Roger Joseph Manning Jr.
Drums: Joey Waronker
Guitar (Acoustic Slide): Smokey Hormel
Guitar (Acoustic): Beck Hansen, Gus Seyffert, Jason Falkner, Smokey Hormel
Guitar (Electric): Beck Hansen, Gus Seyffert, Jason Falkner, Smokey Hormel
Harmonica: Smokey Hormel
keyboards: Jason Falkner, Roger Joseph Manning Jr.
Mandolin: Smokey Hormel
Opening Act: The Ghost Of A Saber Tooth Tiger
Piano: Jason Falkner, Roger Joseph Manning Jr.
Robot: Beck Hansen
Synthesizer: Gus Seyffert, Justin Meldal-Johnsen, Smokey Hormel
Tambourine: Gus Seyffert, Roger Joseph Manning Jr.
Vocals: Beck Hansen
Vocals (Background): Gus Seyffert, Jason Falkner, Justin Meldal-Johnsen, Roger Joseph Manning Jr., Smokey Hormel