The shorter crop of hair on Walter in the flash forward is inconsistent with the longer, messier head of hair he sports when the series finally catches up with the sequence, which only covers just over a day, at the end of the series's run.
At the beginning, as Walter pulls up in front of the house, the contrail of a jetliner can clearly be seen. Moments later, as he gets out of the car, the same region of the sky is completely clear.
Two DEA agents leave Hank's garage and Walter drives towards Hank's house. In that sequence as the camera looks into and out from the garage, the shadow of the house shifts about 20 minutes anti-clockwise then back again.
Before Hank punches Walter, there are remains of red makeup visible around Bryan Cranston's left eye, from a previous take.
In the intro a group of youth skateboarding the empty pool of the former White residence. The pool is curved with a rounded bottom here. In all previous scenes the pool's "footprint" is of rectangular shape and as Skyler walks into in another scene looking as if she'd fix to drown herself, the bottom is flat with edges.
Immediately after being punched, Walt has bloody cracks on his face, but there is no running or dripping blood. The blood has instantly clotted as if the injuries happened minutes ago.
Throughout the series, Hank pronounces his self-named beer, Schraderbräu, like "Schrader-brow." However, because the A has an umlaut above it, its proper pronunciation would be like "Schrader-broy."
As Hank swerves into the driveway during his panic attack, two crew members holding equipment standing are visible in a driveway across the street.
Badger talks about food replicators on Star Trek The Original Series, but they only had food synthesizers. Replicator technology only arrived with Star Trek: The Next Generation.
Skinny Pete is right that tulaberries are from the Gamma Quadrant in the Star Trek Universe, but that reference is from Deep Space 9, not Voyager (which is stranded in the Delta Quadrant.)