Episode #2.8 - S2-E8
Other mistake: Richard states that all 33 of the prints he recovered from the cash wraps were by the victim, but we see the secretary in flashbacks collect them from the garbage bin with no gloves, which would leave obvious prints that can't be washed away - the presence of prints wouldn't even be all that incriminating per se, since it wouldn't be terribly strange for the personal assistant to momentarily handle some money inside her boss' office.
Answer: Most likely they had only tropical exotic drinks, he wanted an old fashioned English beer.