Werner Ziegler's crew blasts the rock preventing construction of the meth lab's elevator, then celebrate because the end of their job is in sight.
He finds that Werner temporarily disabled the cameras with a laser, permitting him to move through the warehouse undetected, cut the padlocks for the doors leading to the roof and escape by climbing down the building's maintenance ladder.
"Wiedersehen" includes the origin story for Hector Salamanca's bell, an item vitally important to the storylines of both Better Call Saul and Breaking Bad.
In this episode, Werner's crew have spray painted the word "Wiedersehen" on the rock they need to blast to make room for the elevator in the underground meth lab, in effect saying "goodbye" to the obstacle that has put them behind schedule.
"Wiedersehen" can also be understood as a reference to Werner's escape, since he is effectively saying goodbye to his crew, to Mike, and to the job of supervising the meth lab's construction.
The site's critical consensus is, "A feeling of inevitability permeates 'Wiedersehen', a surprisingly mellow and melancholy penultimate episode beautifully realized by Vince Gilligan and Gennifer Hutchison's creative reunion.