One is that neither Brenda nor Damon talk about "our" house/bedroom/children. It is always "my" house/bedroom/children. I believe those two have lost any kind of feeling beyond themselves, and seem to have created a cold environment void of any kind of genuine emotion. Their lack of emotion about Danielle and their preoccupation about appearance through the days after she disappeared, is IMO, the only reaction they can generate. The same cold, emotionless personality appears in their callous reaction to the fact that another woman was in bed with Damon in their house only feet from where their children slept.
Another is that there are so many details that I would think would be burned in their minds that they cannot recall, yet can recall with great clarity the night-light that was out so the blinds had to stay open, the door openings and closings and the emphasis put on that even in the 911 call, fer pete's sake.
Third, it's hard to imagine any adult pressing against a 60-lb child's face hard enough to break out her upper teeth in the process of smothering her. I have no clue as to what could have happened to cause the broken teeth, but my guess is it was something other than smothering.
Last, as a computer programmer, a sleazy swinging lifestyle filled with bizarre activity and willing participants, isn't the next logical step to set up a web-site, credit card friendly? Is it beyond the scope to think that a cold, sleazy, sex-obsessed individual could get there?
...late night thoughts...