Dr Grant Seeker was in trouble. He'd planned to bring back the iguanodon back with the guests in their Time Rover. He just hadn't planned on the iguanodon escaping and roaming the halls of the Dino Institute.

If security caught him, he'd be fired. Especially since he went behind Dr Marsh's back and stole her credentials to change the date on the Time Rover.

After bidding goodbye to the tourists, Grant took off down the halls, trying to find the dinosaur he'd brought back.

'Dr Seeker.'

It was Grant's boss, standing at the end of the hallway with her hands on her hips.

Grant's heart skipped a beat and he stopped running, barely avoiding a collision with her.

'Dr Marsh,' he said. 'What a… what are you doing here?'

'You mean you don't know?' asked Dr Marsh.

'Uh, know what?' Grant asked, doing his best to casually rub his neck with his hand, but it came off as suspicious anyway.

'There's an iguanodon loose in the halls.'

'An iguanodon. Really. How interesting,' said Grant.

'You wouldn't happen to know anything about it would you?' asked Dr Marsh.

'Uh, nope. Not at all.' Grant's voice went up a pitch.

Dr Marsh raised an eyebrow. 'Really?' she said. 'I believe earlier you were talking to the guests about going to the late Cretaceous period to recover an iguanodon.'

Grant shook his head. 'No, Ma'am. That's just a weird coincidence.' He chuckled.

Dr Marsh grunted in her expression of disapproval. 'Do something about that iguanodon, Dr Seeker. Or you're fired.'

'It's not my iguanodon,' Grant lied. 'But yes. I will.'

Grant passed Dr Marsh and ran as fast as he could down the left hand hall.

'Other direction, Dr Seeker,' Dr Marsh called out after him.

'Yep!' Grant turned around and ran the other way down the hall, where he saw security wrangling an iguanodon. 'Hey! It's… an iguanodon, what a surprise!' He said, not surprised in the least.

'Is that your iguanodon?' One of the security officers asked.

'Nope. Never seen this iguanodon before in my life,' said Grant. 'Or any iguanodon for that matter.' A bold faced lie. He'd tagged this iguanodon before, weeks back.

Grant chuckled nervously as the iguanodon stared at him in recognition, seeing him as a friend.

'So this is your iguanodon, Dr Seeker,' said Dr Marsh.

'No, Ma'am,' said Grant. 'But I will just take it to my office. For… to study it. I'm a palaeontologist. We don't usually get the chance to study real, um, living dinosaurs.'

'Seeker, I ought to fire you,' said Dr Marsh.

'Yeah I figured,' Grant said with a sigh.

'You undermined me, went behind my back, stole my identity, endangered tourists and yourself, and you brought back a dinosaur. You're lucky I'm not going to the police.'

'So is that it? I'm fired?'

'I can't fire you. Someone needs to look after that dinosaur,' said Dr Marsh, pointing at the iguanodon. 'Having to scoop it's poop should be punishment enough.'

This takes place at the end of the Dinosaur ride at Animal Kingdom, after you've come back from the meteor strike and arrived safely back in 1999 with the iguanodon. Dr Grant Seeker, I can imagine, would be in a whole heap of trouble.
It is heavily implied that Aladar from the Dinosaur movie is the iguanodon you bring back with you from the past.
Title is taken from the obscure Disney movie One of Our Dinosaurs is Missing.