There are actually two errors of continuity with Buffy and Spike's journey back to the Initiative to find the medications Spike needs. First, Spike was captured during Wild at Heart (1999), then wakes up in his cell at the beginning of The Initiative (1999) not knowing where he is and promptly escapes; he didn't even know about the implant until he tried to bite Willow and couldn't. Thus, there were no experiments or medications for him to remember. Secondly, at the end of Primeval (2000) after Adam is destroyed, the government review panel orders the Initiative filled in with concrete. So, even if Spike had any reason to remember some sort of helpful medication, there shouldn't have been an initiative to go back to.
In an earlier show this season (Either "Showtime" or "Potential" when Anya and Giles are leaving the Demon dimension Anya touches Giles shoulder as they come out of the portal. So someone actually did touch Giles and therefore Anya knew he was corporeal...
In the beginning, Anya quips that she didn't realize Molly was so compact but she doesn't actually move her lips.
(at around 14 mins) A camera is visible in the upper left hand corner. (I think that is actually the very top of the guitar being played on stage...)