Ben Affleck Takes Son Samuel to Disneyland After Completing Alcohol Rehab

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Ben Affleck and his son Samuel enjoyed a little father-son time at the Happiest Place on Earth!

The Batman star took his 5 year old to Disneyland on Wednesday, where the two enjoyed a variety of rides, including "Dumbo" and "It's a Small World," ET has learned.

"He seemed to be in a pleasant mood, though he was reserved," an onlooker told ET. "He looked like any other dad at Disney."

EXCLUSIVE: How Ben Affleck Is Doing Post-Rehab: He's 'Very Taken Aback by the Outpouring of Support'

Another onlooker said said Ben was "very engaged with his son," adding, "They were talking to each other a lot while on the different rides."

Just over a week ago, the Justice League star revealed that he had completed a treatment program for alcohol recovery.

WATCH: How Jennifer Garner Helped Ben Affleck Turn His Life Around

"Ben is doing great," a source close to the actor told ET on Wednesday. "He is still very taken aback by the outpouring of support since making his very personal announcement."

"As always, he’s enjoying spending time with his children and friends, and working," the source added.

Affleck revealed via Facebook this month that he had sought out treatment to "be a better father" to his three kids -- Samuel, as well as Violet, 11, and Seraphina, 8.

WATCH: Ben Affleck's History With Alcohol Addiction: A Timeline of the Actor's Struggles and Road to Recovery

"I have completed treatment for alcohol addiction; something I've dealt with in the past and will continue to confront," he shared. "I want my kids to know there is no shame in getting help when you need it, and to be a source of strength for anyone out there who needs help but is afraid to take the first step."

Watch the video below for more on Ben's alcohol recovery.