Blue packs of meth can be seen in Merle's bag of medicine that were actually borrowed from the Breaking Bad (2008) set.
The pack of cigarettes found by T-Dog are labeled Morley, the same brand smoked by the Cigarette Smoking Man in The X-Files (1993).
When T-Dog (Irone Singleton) asks Dale (Jeffrey DeMunn) his age, Dale responds with 64. This is actually DeMunn's age at the time of shooting.
When Daryl takes out Merle's stash to help T-Dogs infection a large amount of blue crystal fills the lower part of the bag. Identical to the p2p cook, blue meth that Walter and Jesse begin to produce in the 7th episode of Breaking Bad (2008).