Burt's outie husband is a completely different actor (or at least has a radically different appearance in Season 2.
The Lumon severed floor lacks mechanical, electrical, and fire protection features that would be found in a modern real-world office building, such as sprinkler heads, firefighting hoses, fire alarms, electrical outlets and panels, exit signs, clearly marked stairwells, and HVAC vents (the one realistic element is the occasional fire extinguisher). While it is unclear if this was done deliberately, the absence of these elements enhances the otherwordly, isolating feel of the sets.
At the end of Season 1, Irving is shown to have information on the identities of a number of Lumen severed employees. There is no explanation provided as of the end of season 2 provided as to where he got that information from.
No explanation is provided for Irving seeing the black paint flowing hallucinations throughout season 1. He's not reintegrated so there should be no reason why he's experiencing them as his Innie would have no knowledge of what his Outie was painting outside the Severed floor until the final episode. None of the other non reintegrated characters seem to be experiencing any types of visions.
Besides "Helly R", the other Severed characters are referred to on by the first initial of their real last name, Mark "S" , Dylan "G". As Helly is Helena Egan, there's no explanation provided as to why she's Helly "R". All the non Severed employees know she's an Egan and the Severed ones wouldn't so there's no explanation as to where the "R" came from or what it means.