Proceedings were briefly brought to a halt during the second inning when the inflatable floated out from the stands and landed on the field at Miller Park.
Keon Broxton, the Brewers outfielder at bat, could not contain his amusement upon spotting the balloon and the game officials were forced to take action.
Umpire Jeff Nelson duly made his way over to the balloon and burst it with one authoritative stamp of his right foot.
Nelson then received warm applause from the crowd with a tip of his cap and play resumed.
The Cubs, defending World Series champions after ending their 108-year drought last November, went on to come out on top in the I-94 derby 7-4.
Jake Arrieta struck out 10 and Kris Bryant had his second three-hit day in a row as the Cubs clinched a second consecutive series victory.
Bryant reached in all four of his plate appearances, singling three times and drawing a walk in the seventh. After starting the season 0-for-13, he went 7-for-12 in the three games at Milwaukee.
Additional reporting by PAReuse content