My homebirth was on Thursday, so this is fairly fresh in my mind.

I wish I'd told DH to put the champagne in the fridge to chill, because my mom cooked breakfast for everyone, and we could have had celebratory mimosas with our midwives, but we all forgot about it. I wish I'd told him BEFORE he rolled out the carpet protector film for the birthing tub that odds were against my labor lasting long enough for us to fill up the pool. Him rolling out the carpet protector took a long time, made a lot of noise, and ended up being a big waste. And then, of course, the package was open and now I can't return it to Home Depot.
In terms of what I wish I'd had at the house, I wish I'd set up more candles in the bathroom instead of the living room, but then, I wasn't planning to deliver in the tub. I just ran out of time to get the pool filled and had to use the tub instead. I wish I'd moved more of the clutter out of the master bedroom, but again, labor moved faster than we thought it would. I wish I'd ordered more of the cold ice pack pads. I only ordered two with the birth kit, and more would have been nice to have. I ended up with a lot of leftover supplies too because I labored/birthed in the tub, so we have a ton of chux pads and other items I may never use.
For our daughter... well, she slept through the whole birth, because it only lasted about 3 hours during the night. So in her mind, she went to bed with a pregnant mama and woke up to a baby in her parents' bedroom. As a result, she has asked us repeatedly if we're really keeping the baby, what happened to the baby that was in my tummy, why isn't the baby in me anymore, etc. I kind of wish that she had been able to come in toward the end, but then, DS had to have CPR after birth, so being there would likely have been traumatic for her. Had she been there in the room, I know I'd regret that we didn't prepare her for the possibility that something could go wrong with the birth and that the midwives might have to work on the baby for a while.