The hit series -- currently in its 7th season -- hasn't been shy when it comes to elaborate costume pieces ... even winning Emmys for their hard work! However, this season might've gone too far.

With celebs wanting to go all out with their looks, the team is forced to make things bigger and better ... which has proven to be a disadvantage for contestants, including Cyclops and McTerrier.

Both mystery celebs have had their share of tumbles and slips while in costume ... and there's concern more wipeouts are inevitable.

Cyclops' headpiece is a beast, too ... making it impossible to enter and exit the stage as the other contestants would. Instead, crew members have to move equipment around just for them to walk on stage.

We're told the choreographers are also bearing the brunt of the problem ... forced to simplify performances because the costumes are just too difficult to manage.

Production sources say first rehearsals are usually rough when celebs break in their new attire ... but this season has been especially difficult due to the increasing complexity of the costumes.

This isn't the first time elaborate costumes gave the show some grief ... as we reported, last season's Jester -- AKA  Johnny Rotten of the Sex Pistols -- had a bulge just too big for TV audiences, forcing costume designers to shrink the ... royal jewels.