Discipline cost Leinster
The Irish province also conceded 15 penalties in their 9-24 loss to Toulon in a European Champions Cup showdown.
No fewer than nine of the penalties came at the break down, an area which Cullen says he will have to review before Saturday's return fixture in Dublin.
"We hope to have close to 45,000 fans watching us [in Dublin] and we want to put in a performance that we can be proud of," Cullen said.
"A lot of break down calls went against us and we will have to work on that interpretation," he added.
"A lot of effort went into that performance, so it is pretty frustrating.
"We struggled to manage the game in the second half.
"It is difficult when you have 15 penalties against you away from home.
"We just need to focus on our next performance and it is going to be a huge challenge with only a six day turn around."
It was Leinster's third successive defeat in the Champions Cup this season – the first time they have lost their opening three games in a Pool and the first time they have lost three games in a row in a season since 1998/99.
With only one point from those three matches they can now only finish with a maximum of 16 points.
Source: @ChampionsCup
