Most of the illuminated devices depict a character making an obscene gesture.
Peter Berdovsky, 27, of Arlington, and Sean Stevens, 28, of Charlestown, were each arrested Wednesday night on one felony charge of placing a hoax device and one charge of disorderly conduct, state Attorney General Martha Coakley said.
In a news release announcing Stevens' arrest, she said the men worked together to place the devices. At an earlier news conference she said Berdovsky had been hired to place the devices.
Berdovsky posted video on the Web of him placing the devices around Boston, reports The Early Show correspondent Joie Chen.
Highways, bridges and a section of the Charles River were shut down and bomb squads were sent in Wednesday before authorities declared the devices were harmless.
"It's a hoax — and it's not funny," said Gov. Deval Patrick, who said he'll speak to the state's attorney general "about what recourse we may have."
Turner Broadcasting, a division of Time Warner Inc. and parent of Cartoon Network, later said the devices were part of a promotion for the TV show "Aqua Teen Hunger Force," a surreal series about a talking milkshake, a box of fries and a meatball.
"The packages in question are magnetic lights that pose no danger," Turner said in a statement, issued a few hours after reports of the first devices came in.
The devices were planted in nine other cities, but with far less dramatic results, reports Chen.
New York, Los Angeles, Chicago, Atlanta, Seattle, Portland, Ore., Austin, Texas, San Francisco and Philadelphia all had the devices for the past few weeks.
"We regret that they were mistakenly thought to pose any danger," the company said.
Complicating all of this, adds CBS News correspondent Bob Orr, is a separate bomb scare that happened earlier Wednesday at the Medical Center in Boston. Officials say a disgruntled employee is suspected of planting a phony pipe-bomb. It was not a real explosive.
The marketing company responsible for the campaign, Interference Inc., had no immediate comment. A woman who answered the phone at the New York-based firm's offices on Wednesday afternoon said the firm's CEO was out of town and would not be able to comment until Thursday.