It was all a ruse. Betty-R wasn't looking for other ways in to the base all along, although she and Eric-R found one. It was one of the missile silo hatches, which George-R managed to work out how to open. Quite why both Eric-R and Betty-R had to fall through the newly discovered entrance is unclear, but at least Eric-R broke Betty-R's fall, and his neck in the process. The slime mould sofa is fed again.
Betty-R actually just wanted an excuse to leave the silo and search for Stan-U's secret base. So did Eric-R, but his clone replacement means he now trails Betty-R by a small amount. Enough for them both to bump in to each other on the way to the secret base, and both manage to convince each other that they are still following the mission of maintaining silo 543. The duplicity is heart-warming.
Once inside Stan-U's surprisingly easy-to-find secret base, the pair find Stan-U. Betty-R's plan is to shoot him. Eric-R's plan is to stop Betty-R from shooting Stan-U, and to do so physically. He succeeds, but by 'physically' Eric-R probably imagined himself wrestling Betty-R's gun free and not getting himself between Betty-R's laser pistol and Stan-U. Eric-R's left forearm is vaporised. Don't worry, Eric-R! The laser cauterises the wound.
'It's a good thing I wasn't left-handed.'
Make a roll.
'No. Being left-handed is treasonous. I wasn't left-handed.'
Make a roll.
'I get 19.'
You are left-handed. Were left-handed. Your treasonous nature has been corrected. All praise Friend Computer!