yes. you need a hour and a ticket to take the RER literally from the heart of twon (opera or gare de lyon) to the doorstep of the park. I think the last trains leave at midnight. It's very well thought out and takes the hassle out of needing a car at all.
"As usual he's taken over the coolest spot in the house"- Father re: Orville 1963
The Chatelet Les Halles station (not to be confused with the Chatelet station) is in the heart of Paris & has a metro & RER-A train line so use that station. The RER is not labeled until you enter the station so don't be fooled at first by the METRO signs. Read the signs carefully. You'll want the "RER A4" (Marne La Vallee - 'Chessy' train station: Parc Disneyland). The signs inside the station have multiple destinations with boxes next to each of their names. The approaching train will travel to the destinations who's boxes are lit. So if you see a train approaching but "Marne La Vallee" is not lit up, then the that train is not the RER A4, so don't board. The video monitors in the station tell you the name of each train (ex: "OBNE") as well as what time they're arriving and their final destination. Once you get on the RER A4, it'll be about 30 minutes til you reach Euro Disney, so just relax for a bit. You'll know you're out of Paris when the train comes out from underground. Once you arrive at the Chessy (Euro Disney) station, exit out of the station and go to the Disneyland Hotel. The ground floor of the main building is also the ticket booth & entrance to the park. One final note: DONT LOOSE YOUR TRAIN TICKET! You'll need it to exit the train station.