Why is Rose not a very good actress? She's the only member of the initial team that wasn't a criminal before. All of the others would've had plenty of time to get good at lying through their teeth, but all Rose had was three weeks.
How did Debbie convince Lou to go through with stealing the Toussaint after Lou found out about the "revenge" aspect of the job? By telling her that it wasn't the real prize in the first place. But, it was the best way to get the others on board and serve as a distraction for the actual prize—the other royal jewels that were also on display. While individually they were less expensive, their quantity and value exceed the Toussaint by itself, ultimately being the bigger prize.
Viewers who are history buffs (or just fans of Puppet History) will notice that one of the exhibit's mannequins features a replica of the diamond necklace of Marie Antoinette that was at the center of a scheme in the 18th century. Like the Toussaint, after the con artists acquired it, they chopped it apart and fenced it in pieces. It shows up again, at the very end of the movie, among the other stolen jewels in Lou's fridge.
Danny's tombstone tells us he died in 2018. Assuming the film takes place in 2018... that means it happened shortly before Debbie got out of prison, and she didn't get to attend her brother's funeral.
Debbie might have gotten compassionate leave (it's been known to happen, and she was jailed for a non-violent crime); but if she did attend, it would have been with armed guards. Not exactly conductive to mourning or bonding with the family members - and possibly proving dangerous to the other members of the Eleven (who would have all turned up). It's possible that Debbie could have attended but chose not to to keep everyone else safe.
that was at the center of a scheme in the 18th century. Like the Toussaint, after the con artists acquired it, they chopped it apart and fenced it in pieces. It shows up again, at the very end of the movie, among the other stolen jewels in Lou's fridge.