Factual error: All of the computers show a Mac OS when they're booted up. However, when Peter is shutting his computer down to try to escape his boss, the computer shuts down to a C: prompt. For those not technically minded, a C: prompt is only seen on IBM-compatible PCs, never on Macs. (00:19:20)
Factual error: When Peter is fishing, the fish being caught is a largemouth bass. When he holds the fish up in the office, it is a striped bass.
Answer: They never told Milton he was fired, they just cruelly cut off his paycheck, figuring he'd eventually get fed up and leave (he'd actually been laid off years ago, but a payroll glitch kept him getting a paycheck). The management is hoping if they're cruel enough, he'll stop showing up.
Brian Katcher
This is actually the reverse of what happened. The glitch caused him to continue to receive a paycheck, even though he'd been laid off. The "Bobs" corrected the glitch, so he would no longer receive a paycheck. In an effort to avoid confrontation, they chose not to say anything to him, hoping he'd realise it and leave on his own.