Always keep an eye on kids during the diaper change, there are 101 things that can happen with kids. Kids may chew on the wet wipes, chuck some poop at you, the possibilities are endless. Better to be safe than sorry!
Never leave a child alone on a sofa, table, bed or anywhere that kids can roll and fall off from; especially during diaper change.
Keep hazardous items (coins, keys, medication) in a secure place out of child's reach.
Most diaper bags are made with quality workmanship but they do contain small parts such as zippers which may cause choking when detached.
Detach marlin's sling straps when not in use. Most diaper bags come with slings which may cause accidental strangulation.
You should not be carrying more than 10% of your body weight as studies have shown anything above 15% may cause back issues.
Don't hang heavy bags over the handles of the stroller; the sudden weight shift may cause the stroller to tip.