Literally. Sometimes he will ascribe himself properties I have, and make me the child--he'll say "I'm a grown-up", "You can't sit in the front seat [in our car], it's not safe, I have to sit in the front seat, you have to sit in the back seat." "This is my office. Sorry you can't come in I have work to do." That's cute perhaps but other times he will say "My name is [Eric's Dad]". Last night, he told me that his name was [Eric's Dad] and that he had a four-year-old baby named Eric, who was crying. Eric himself had been earlier. So he is in some way projecting himself onto me. Is this indicative of any kind of dissociative issues? Or is it just 'cute'?
Kids that age learn a lot by imaginative play. It's how they make sense of the world and experiment with different responses to events. Pretending to be an adult is very common. Playing along is a good opportunity to show empathy and teach better responses. You might say,
I'm Eric. I'm sad because I couldn't find my toy. I wonder if I should cry or ask my dad to help me find it.
This is how kids open up to you. Take advantage of it while it's still relatively easy.
It tells just how much he sees you as role model. Instead of seeing this as abnormal you should be the role model he deserves.
Other than that do understand that this behaviour will stop after some time. You only need to worry if this does not stop and causes complications.
Hope I helped.
P.S.: When I was a child I used to wear my father's army uniform. It made me feel grownup just like him. Now that I am older I feel different but I just want you to know that this is stage all children go through so don't worry.
I'm not a parent myself, but two points:
1) You could argue that no, it's not just 'cute'. Imagining yourself in someone else's position is the very basis of empathy and all that is worthwhile in humanity :-)
2) Describing himself in the third person, from the POV of you or someone else, can sometimes be a mechanism to put distance between himself and things he's not otherwise able to talk about. In this case, he talked about himself crying in the third person. It's good that he can reflect on this. That's not a dissociative disorder, it's a means of talking about or thinking about strong emotions without reliving them. The same goes if he says there's something wrong with his toy: consider carefully what he's telling you, but first in the spirit of "is this troubling him?" and not "why is he expressing it in this way?".
Dissociative disorders are (loosely) when he loses contact with his identity and feelings, not when he imagines or imitates others, or when he intentionally considers himself as an outsider would. Standard psychiatric advice from a non-specialist: if you're concerned then of course look for combinations of symptoms and for situations where the suspected issue actually causes him problems. Then ask someone who knows what they're talking about and can consider him specifically.
Oh yes, and:
3) He has to sit in the front of the car and you can't go into your office? He knows the rules and he's flagrantly trying to turn them around in his favour. It's a nice try, I bet he's ecstatic every time it works for even a second ;-) Basically he's reinvented the Lord of Misrule. AFAIK this is not in any way unusual, it's common sense to want whatever good stuff he sees that you have.
Is this indicative of any kind of dissociative issues? Or is it just 'cute'?
It may be that it is something other than cute or "broken". It may be a limit of the communication ability.
My 2 year old daughter sometimes speaks, not as things are, but as she wishes they were. She could say "I'm big" or "I'm grown up". She doesn't have the language specialization to communicate well so this gets a little muddled. I find out by asking questions.
Examples from my daughter:
She says: "that is my cupcake"
I say: "it belongs to the store. Would you like to have it"
She says: "yes. Please."
I say "okay"
She says: "I'm all grown up."
I say: "Are you all grown up"
She says (sadly) "No."
I say: "You are growing up so fast. You are so big."
She smiles big, and brightens.
She knows what is, the problem isn't that. the problem is that language is a blunt instrument when you are a 2 year old.
As an aside, I don't believe in broken at that age. In my head there is a substantial difference between "damaged" and "broken" because damaged can be repaired, resolved, and made so things work as well as if nothing had happened while broken means there will always be scars, echoes, and indication, sometimes gross indications, of whatever the system was.