Factual error: Mulder tells Scully that he is trying 27828 and it is not working. It is not surprising that it is not working, because the Napier constant is not 27828, it is 271828. Plus they somehow they know how many digits from this constant should be entered on the keyboards.
Character mistake: Mulder asks Scully about "the fourth commandment about obeying the Sabbath, the part when God made heaven and Earth " However, Scully as a Catholic should know that this is the third commandment for Catholics. This is also an indirect indication that Mulder was raised in Jewish religion.