Well... it's easy to say the words, "I'm sorry." It takes longer to learn what they really mean. Some people catch on when they're, say, about thirty-five, but don't expect him to understand much of it at three. It may be enough that he knows the words right now.
Three-year-olds are into testing limits, anyhow - some more than others. You may need to define very clearly what the limits are. Some toddlers hit to get attention; negative attention is better than none at all. So you might want to think about how to give him positive attention. You're probably giving a lot. Think about how you can possibly fine-tune it.
But wait, there's more.
Some things are not even good for negative attention. For instance, hitting somebody (Mama or anybody else) is wrong and the consequence is... (figure out what it is - not too harsh and not too cushy, and something YOU can stick with every single time).
Then you want to teach him to be attentive to you. That means that he listens to what you say, whether he likes what you say or not. You may need to tell him what you are teaching him: "You need to learn to listen to what I say." Then during the day, get his attention (he must look at you for you to know you have his attention), tell him something, and get him to repeat back what he heard. Do a lot of this for a couple of weeks.
Whenever you have to move him from one activity to another, try notifying him in advance: "Ben, it will be time to leave the playground/pick up toys/take a bath in five minutes." (He has no idea what five minutes means, but the idea is for him to listen to you when you say, "Leave the playground.") "Ben, it will be time to leave the playground/whatever in one minute." "Ben, it's time to leave the playground. Let's go." If he happens to get up and get ready to leave, praise him a lot! If he resists, you can say something like, "That's too bad," and take him home. Then you can let him know that because he didn't listen to you, he won't be able to go to the playground tomorrow. (Tomorrow is a very long time.) Maybe the day after tomorrow he can try again. That's the general idea.
You are matter-of-fact through all this. You're not mad at him, so he doesn't have to try to make you happy. He doesn't have to do anything but learn to be attentive and then obedient.
The thing about the sort of bribery you mention is that it's usually a bust. It's all right for you to say, on occasion, "I'm so pleased with the way you listened to me - let's stop for an ice cream cone on the way home." That's totally *your* choice, and in *your* control. But you don't want to put yourself in a position in which *he* dictates the conditions of obeying. That's contrary to what you want him to learn. Future treats are no match for present fun, anyhow.
This will be harder on you than it will be on him, even without the hitting. But press on.