Your toddler is at one of the most fun parts of childhood. Everything is fun, except baths of course, and the imagination and innocence of childhood is at its peak. If you have older kids, or have any in your extended family, your toddler is going to want to do everything they do and have the same things they do. You may not think about sleeping bags for toddlers, but if your older kids have some, they are going to be asking. If you want to get them something, be careful of the model that you buy. Just keep a few simple safety things in mind so they can be safe while being just like the big kids.
You know many items on the market can be marked for ages two and up. These are often about choking hazards. However, toddlers are still prone to accidents and you do have to keep things safe for them. That being said, remember that any sleeping bags for toddlers that have any type of draw string should be avoided. They could easily get this around their neck and cut off air while sleeping. You may even want to make sure that no sleeping bags in your home have any long strings for that very reason. Long strings have no place near any sleeping person of any age.
Some sleeping bags are made with a slippery outer shell. These are fine for most kids, but may not be the best idea for sleeping bags for toddlers. The reason being is that this material is very slippery and a sleeping toddler can move quiet a bit. This won't matter on the floor, but they will want to use their sleeping bag on the bed, the couch, and anywhere else they lay down. They could slip off get hurt very easily. Get a bag made with a material more suited to staying put, like you would use for their sheets and blankets on their bed.
Some zippers are better than others when it comes to sleeping bags for toddlers. This is not so much a safety issue, though it can be, but rather more a longevity issue. Many of the less expensive models of sleeping bags you can buy for kids of any age are going to have zipper issues. Many break very easily because they are not well made and kids can be very hard on zippers. Look for a better quality bag that has zippers or other closures that look like they can take the beating only younger children can hand out.
Lastly, you may be tempted to get the shortest bag you can find when you are shopping for sleeping bags for toddlers. You may also want to get one with their favorite TV character on it. These are both bad ideas if you want the bag to last. Toddlers grow quickly and their likes and dislikes change quickly as well. Get something neutral and that they can grow into, especially if you intend to spend a little extra to get a quality sleeping bag. This allows them to use it for years on end before you have to replace it.