Gladiator

A former Roman General sets out to exact vengeance against the corrupt emperor who murdered his family and sent him into slavery.

There are 3 scenes having someone outside the Colosseum juggling balls in the background.

At 1:08:58, he appears to attempt 5 balls unsuccessfully, but over the next 30 seconds, we see him 3 more times juggling 3 balls with a few simple tricks.

At 1:25:46, just after a scene change to the Colosseum starting with someone blowing fire, we see the juggler in the far distance on the right side, juggling 3 balls for about 4 seconds.

At 2:11:02, another scene change to the Colosseum begins with our juggler doing 3 balls for about 6 seconds, with a few tricks, including a quick Mill's Mess, apparently predating its invention by over 2,000 years.

The entire movie may be seen here.