Twinning most commonly refers to crystals that are merged together, as if one has sprouted from within another.
Jim Irwin is shown as being very dehydrated after one of the moonwalks. This is accurate: the drinking water supply in his suit failed and he wasn't able to drink during his very strenuous activities. This was recorded for the rest of his flight as irregular heartbeats and is attributed to previously undetected heart issues that led to one heart attack two years after the mission and several more later, all experienced during strenuous physical activity, and which ultimately cut his life short. He was the youngest of the Apollo moon crews and, at the age of sixty-one, the first of them to pass away.