Maxwell, who was yelping in agony as medical staff rushed in to inspect the damage, may yet play a part in the dead rubber against South Africa on Saturday but Marsh's World Cup is over.
Former captain Steve Smith was also nursing a sore pinky finger after slips fielding practice, and stopped a few balls into his net session to get strapping on his hand, Australian media reported.
Langer, a gritty former test opener, saw his fair share of bruising nets sessions in an all-conquering Australia team, and his practice against the likes of Glenn McGrath and Brett Lee would have helped him carve out an outstanding career of 105 tests and 23 centuries.
He had a more philosophical take on the friendly fire than Australian media, who were quick to declare an "injury crisis" at the World Cup.
"It’s actually a benefit to us," Langer told reporters.
"It’s unfortunate we have accidents in the game, and in all sports you have accidents, but that’s what we pride ourselves on, we train really hard so we’re right for the games.
"We always say you train hard, you play easy.
"So if you can play against the best bowlers in the world, then that hopefully makes the job in the middle a lot easier."
Marsh will be disappointed to be heading home early but the collective toll may be negligible.
The 35-year-old lefthander played only two matches against Sri Lanka and Pakistan when all-rounder Marcus Stoinis was ruled out with a side strain.
Australia have drafted in a ready-made middle order replacement in righthander Peter Handscomb, who has been touring with the Australia A side in England and some felt unlucky not to be picked in the initial World Cup squad.
A scan cleared Maxwell of serious damage but selectors might opt to rest him as a precaution ahead of the semi-finals.
A win over South Africa would almost certainly mean Australia lock in a semi-final against New Zealand at the same ground, which might be preferable to the prospect of an England semi-final at Edgbaston given the hosts' return to form.
Captain Aaron Finch said the nets session injuries were not ideal but the batsmen needed to be ready to face top-shelf quicks like India's Jasprit Bumrah and South Africa's Kagiso Rabada.
"You still have to prepare every game the same and you don’t want to feel underdone walking out to the middle," he said.
(Reporting by Ian Ransom; Editing by Peter Rutherford)
