Episode #2.5 - S2-E5
Revealing mistake: When Ben Miller asks for the forensics report on the oyster and shot glass, the report has egregious spelling mistakes ("Specimin" instead of Specimen) and shows the victim testing positive for Oxycodone rather than strychnine! For the record, it is an entirely different lab test (a real one, with 'specimen' spelt correctly) done for a patient under prescription medications (morphine, oxycodone and benadryl) and its date is inconsistent with every other episode (it's a 03/19/2010 document and in the first season it was established the year was 2011), but these last details can be noticed only if you freeze-frame. (00:42:00)
Answer: There's probably no particular reason. Sets and props on long-running TV shows often change as needed and for various reasons throughout a series run.
raywest ★